The Mid-Autumn Festival falls on the 15th day of the eighth lunar month. Because it is just half the value of Sanqiu, it is named. It is said that the moon is closest to the earth this night, and the moon is the largest and brightest, so there is a custom of drinking and enjoying the moon since ancient times.

Seasonal speaking, the Mid-Autumn Festival is the "Autumn Harvest Festival", and the grain sown in summer sowing in spring should be harvested in autumn. Since ancient times, people have been drinking and dancing in this season to celebrate the harvest with joy, which is described in the earliest poetry collection "The Book of Songs" in China.

From the origin, the Mid-Autumn Festival is also the "Festival of Sacrificing the Moon", which originated from the worship of nature by ancient humans. In the ritual system of ancient emperors, there were two festivals in spring and autumn: spring festival to the sun and autumn festival to the moon.

At first, the day of offering sacrifices to the moon was on the "autumnal equinox", which is different every year in August, so there is not necessarily a moon on the autumnal equinox. It is a big spoil to offer sacrifices to the moon without a moon, and it is gradually established that the day of offering sacrifices to the moon is fixed on August 15th.

From the scientific observation, the inclination of the earth and the sun increases in autumn, and the warm and humid air over China gradually fades, while the northwest wind is still very weak. In this way, when the moisture has gone and the dust has not started, the air is particularly fresh, the sky is particularly clean, and the moon looks round and big, which is the best time to enjoy the moon.