The change of Xuanwu Gate took place in the ninth year of Wude in Tang Gaozu (626). In 617, with the support of Li Shimin, Li Yuan rose up against Sui in Taiyuan and quickly occupied Chang 'an. In 618, after Emperor Yangdi was killed, Li Yuan established the Tang Dynasty and made his son Li Jian a prince. It is said that it was Li Shimin's strategy to arise in Taiyuan, and Li Yuan promised to make him a prince after the job was done. But after the world was pacified, Li Shimin's fame grew, but Tang gaozu hesitated. Li Jiancheng immediately joined forces with Li Yuanji to crowd out Li Shimin. Tang gaozu's indecision also made the DPRK-China decrees conflict with each other, which accelerated the confrontation between the philosophers. That year, Li Jiancheng suggested to Tang gaozu that Li Yuanji should be the commander-in-chief to go to the Turks, so as to seize the military forces of the king of Qin and then take the opportunity to get rid of Li Shimin. Li Shimin decided to strike first at last stand in a critical moment. Only three days after the Xuanwumen Incident, Li Shimin was appointed as the Crown Prince and took over the actual control of the government from his father. On the ninth day of August, Tang Gaozu abdicated, and Li Shimin became the second emperor of the Tang Dynasty, Emperor Taizong. Emperor Taizong was afraid of Wei Zhi. On one occasion, he caught a bird to play with, and suddenly Wei Zhi came. He was afraid that Wei Zhi would say that he was doing nothing, so he immediately hid the bird in his sleeve and pretended to be serious. In fact, Wei Zhi had already seen the bird, so he deliberately talked for a long time with Rory, and then left. By the time Emperor Taizong took it out of his sleeve, the bird had already suffocated.

Later, when Wei Zhi died, Emperor Taizong was very sad. He said, "People can dress their clothes with bronze as a mirror; Taking the past as a mirror, we can know the rise and fall; Take people as a mirror, you can know the gains and losses. Wei Zhi died, and I lost a mirror! "