Postal Code: 318000 Sanmen County is located on the northeastern coast of Taizhou, with Tiantai Mountain to the west, Sanmen Bay to the east, Ninghai County to the north, and Linhai City to the south.

It is 50 kilometers wide from east to west and 38 kilometers long from north to south, with a total area of ??1,072 square kilometers.

The coastline is 167 kilometers long, the sea area is about 500 square kilometers, and there are 122 coastal islands.

The terrain is high in the northwest and low in the southeast; the middle and west are low hills and hilly areas with small valleys and flatlands in between; the east is the coastal plain with crisscrossing rivers and fertile soil.

It has a subtropical monsoon climate and is frequently affected by typhoons.

Historical evolution Sanmen has a long history.

The unearthed cultural relics from Jiankeng Mountain in Liu'ao Town, Baojiashang Fengdun in Tingpang Town, Genshao in Shaojiashan and Manshan Island prove that humans have thrived in the land of Sanmen in the Neolithic Age.

Xia, Shang and Zhou were the territories of Ouyue.

During the Spring and Autumn Period and the Warring States Period, it was the Yue Kingdom. In 306 BC, Chu destroyed Yue, and the Wuqiang princes scrambled to establish themselves. At that time, it was the territory of East Yue.

During the Qin Dynasty, Sanmen was the territory of Dongyue and belonged to Minzhong County.

In the third year of Emperor Hui of the Han Dynasty (192 BC), he was established as the King of Donghai, with his capital in Dongou (now Wenzhou). He was called the King of Dongou in history and belonged to the Dongou Kingdom at that time.

In the sixth year of Jianyuan, King Ying of Minyue was executed, and Ying's younger brother Yu Shan was made King of Dongyue. At that time, it was the territory of Dongyue, which belonged to Kuaiji County and was subordinate to Yangzhou.

In the sixth year of Emperor Wu's Yuanding reign (111 BC), Yu Shan, the king of East Yue, rebelled. In the first year of Yuan Feng (110 BC), he killed Yu Shan and moved his people to the Yangtze and Huaihe Rivers, leaving the land of East Vietnam empty.

In the second year of the First Yuan Dynasty of Emperor Zhao (85 BC), Huipu County was established in Dongou land and governed Zhang'an. At that time, it was Huipu County and belonged to Kuaiji County.

During the Guangwu period of the Eastern Han Dynasty (AD 25-57), it was changed to Zhang'an County, Huipu County, and was then called Zhang'an County.

During the reign of Emperor Wu of the Three Kingdoms (AD 222-252), the western part of Zhang'an County was divided into Linhai County. At that time, it was the territory of Linhai County and belonged to Kuaiji County and Yangzhou.

In the second year of Taiping (AD 257), the young emperor, the eastern part of Kuaiji County was divided into Linhai County. At that time, it belonged to Linhai County and was under the jurisdiction of Yangzhou.

In the first year of Dakang (AD 280), 800 households in Yinxian County and 200 households in Anbei Township in Linhai County were placed in Ninghai County. At that time, Sanmen belonged to Linhai and Ninghai counties and belonged to Linhai County.

In the Sui Dynasty, the county was abolished as a state, Linhai County was abolished and renamed as Chuzhou, and Dongyangzhou was changed to Wuzhou. Ninghai County was abolished, and it was Linhai County at that time, which belonged to Chuzhou and was under the jurisdiction of Wuzhou.

In the twelfth year of Kaihuang's reign (AD 592), the state was changed to Kuozhou.

In the first year of Emperor Yang's Daye (AD 605), the prefecture was changed into a county, Kuo Prefecture was abolished, and Yongjia Prefecture was established. At that time, it was Linhai County and belonged to Yongjia Prefecture.

In the first year of Wude in the Tang Dynasty (AD 618), Linhai County was established as Haizhou. In the fourth year of Wude (AD 621), Linhai County was divided into Linhai County and Ninghai County was restored to govern Haiyou. In the same year, Yongjia County was changed to Kuozhou.

At that time, Sanmen belonged to Linhai and Ninghai counties, and was under the jurisdiction of Haizhou.

In the fifth year of Wude (AD 622), Haizhou was renamed Taizhou. In the seventh year of Wude, Ninghai County was abolished and merged into Zhang'an County. In the eighth year, Zhang'an County was abolished and merged into Linhai County. At that time, it was Linhai County and belonged to Taizhou.

In the first year of Zhenguan (AD 627) of Emperor Taizong, Taizhou was under the jurisdiction of Jiangnan Road and governed Suzhou.

In the first year of Yongchang of Empress Wu (AD 689), Ninghai County was divided into the northeastern part of Linhai County and governed Guangduli (now Chengguan Town, Ninghai). At that time, Sanmen was divided into Linhai and Ninghai counties, which belonged to Taizhou.

In the first year of Tianbao (AD 742), Taizhou was renamed Linhai County.

In the first year of Qianyuan of Suzong (785), Linhai County was renamed Taizhou.

In the same year, the Zhejiang East Road was established to govern Yuezhou, which at that time belonged to Taizhou and was under the jurisdiction of Zhejiang East Road.

During the Song Dynasty, two Zhejiang roads were established in Zhejiang.

In the seventh year of Xining reign of Shenzong (AD 1074), Liangzhe Road was divided into Liangzhe East Road and Liangzhe West Road. At that time, it belonged to Linhai and Ninghai counties and was under the jurisdiction of Taizhou.

The local administration of the Yuan Dynasty implemented the "provincial" system. In the fourteenth year of Emperor Shizu's reign in the Yuan Dynasty (1277 AD), Taizhou was renamed Taizhou Road, and a general administration office was set up to govern Linhai.

Shisanmen belongs to Linhai and Ninghai counties, Taizhou Road, and Zhejiang East Road of Zhongshu Province.

The local government system of the Ming Dynasty was inherited from the Yuan Dynasty, and Taizhou Road was renamed Taizhou Prefecture.

The Qing Dynasty inherited the Ming Dynasty and established four roads: Hangjiahu, Ningshaotai, Jinquyan, and Wenchu. At that time, the three gates were Linhai and Ninghai counties, which belonged to Taizhou and belonged to the Ningshaotai Road in Zhejiang.

At the beginning of the Republic of China, Sanmen still belonged to Linhai and Ninghai counties.

In July of the 29th year of the Republic of China (AD 1940), 18 townships in the southeast were separated from Ninghai County, 5 townships were separated from the northeast corner of Linhai County, and 6 townships in the original Nantian County were established, and Sanmen County was established to manage healthy ponds.

In September, it was moved to Haiyou Town and placed under the jurisdiction of Taizhou (Sixth) Administrative Supervision District.

Sanmen was liberated on February 17, 1949, and the Sanmen County People's Government was established. It was the first liberated county in Zhejiang Province and was under the jurisdiction of Taizhou Prefecture.

In April 1952, Nantian District was placed under the jurisdiction of Xiangshan County.

On May 22, 1954, the Taizhou Commissioner's Office was abolished, and Sanmen County was placed under the jurisdiction of the Ningbo Prefecture.

In July 1957, the Taizhou Commissioner's Office was restored and Sanmen County returned to its jurisdiction.

In December 1958, the organizational structure of Sanmen County was abolished and merged into Linhai County, under the jurisdiction of Wenzhou Prefecture.

On June 4, 1962, the State Council approved the restoration of Taizhou Prefecture and Sanmen County.

In January 1970, the Taizhou Regional Revolutionary Committee was established, under which Sanmen County belongs.

In September 1978, the Taizhou Regional Administrative Office was reestablished and Sanmen County belonged to it.

In May 1983, Shaliu Commune in Ninghai County was placed under Sanmen County.

In August 1994, with the approval of the State Council, Taizhou was evacuated and established as a city, and Sanmen County was affiliated to Taizhou City.