The 15th day of the eighth lunar month is the traditional Mid-Autumn Festival in China and the second largest traditional festival in China after the Spring Festival. August 15th is in the middle of autumn, so it is called Mid-Autumn Festival. The ancient calendar in China called August in the middle of autumn "Mid-Autumn Festival", so the Mid-Autumn Festival is also called "Mid-Autumn Festival". On the night of Mid-Autumn Festival, the moonlight is bright. The ancients regarded the full moon as a symbol of reunion, so August 15 was also called "Reunion Festival". Throughout the ages, people often use "full moon" and "lack of moon" to describe "joys and sorrows", and vagrants living in other places also rely on the moon to express their affection. In the Tang Dynasty, Li Bai's poem "Looking up, I found it was moonlight, and then sinking back, I suddenly remembered home" and so on, "He knows that the dew will be frost tonight, and the moonlight at home is so bright!" Written by Du Fu, there is also "Jiang Nanan spring breeze is green, when will the bright moon shine on me?" In the Song Dynasty, Wang Anshi wrote all the eternal songs. Mid-Autumn Festival is an ancient festival, and it is an important custom to offer sacrifices and enjoy the moon. Ancient emperors had a social system of offering sacrifices to the moon in spring, and folks also had the custom of offering sacrifices to the moon in the Mid-Autumn Festival. Later, it was more important to enjoy the moon than to sacrifice it, and serious sacrifice turned into light entertainment. The custom of enjoying the moon in the Mid-Autumn Festival prevailed in the Tang Dynasty. Many poets wrote poems about the moon in their masterpieces. In Yue Bai, the activities of enjoying the moon in the court and among the people were more extensive in the Song, Ming and Qing Dynasties. So far, there are many historical sites in China, such as Yue Bai Altar, Moon Pavilion and Moon Tower. The "Moon Altar" in Beijing was built during the Jiajing period of the Ming Dynasty, and was used for royal sacrifice to the moon. Whenever the moon rises in the Mid-Autumn Festival, a box is set up in the open air, with moon cakes, pomegranates, dates and other fruits on the console table. After Yue Bai, the family sat around the dining table, chatting while eating and enjoying the bright moon. Now, the activities of offering sacrifices to the moon in Yue Bai have been replaced by large-scale and colorful activities of enjoying the moon by the masses. Eating moon cakes is another custom of festivals, symbolizing reunion. Since the Tang Dynasty, there have been more and more researches on making moon cakes. Su Dongpo wrote in a poem: "Small cakes are like chewing the moon, and there is pulp in the cake", and Yang Guang copied in Qing Dynasty: "Moon cakes are filled with peach meat and ice cream is sugar paste". It seems that the moon cakes at that time were quite close to now. According to historical records, the word "Mid-Autumn Festival" first appeared in the book Zhou Li. It was not until the Wei and Jin Dynasties that the Mid-Autumn Festival became a fixed festival, and it was not until "Yu Shang Shu Zhen Niu Xiao, Mid-Autumn Festival and Early Tang Dynasty" was told. The Book of Emperor Taizong recorded the Mid-Autumn Festival on August 15. The prevalence of Mid-Autumn Festival began in the Song Dynasty, and it became one of the major festivals in China in the Ming and Qing Dynasties. This is also the second largest traditional festival in China after the Spring Festival. August 15 is the Mid-Autumn Festival, and people send moon cakes to each other to show their reunion. "A Brief Introduction to the Scenery of the Imperial Capital" also said: "On August 15th, the moon was sacrificed, the cakes were round, the melons were wrongly divided, and the petals were carved with lotus flowers. ..... Those who get married and stay at home will return to their in-laws in the future. This is the so-called reunion festival. On the night of Mid-Autumn Festival, there is a custom of "reunion" in most parts of our country, that is, flipping a small cake symbolizing reunion, which is similar to a moon cake. The cake contains sugar, sesame, sweet-scented osmanthus and vegetables, and the moon, sweet-scented osmanthus tree and rabbit are pressed outside. After the Mid-Autumn Festival, the elders at home will divide the cake into pieces according to the number of people, and each person will have one. If someone is not at home, leave one for them to show family reunion. During the Mid-Autumn Festival, there are fewer clouds and more fog, and the moonlight is bright and bright. In addition to a series of activities such as enjoying the moon, offering sacrifices to the moon, eating moon cakes and wishing for reunion, there are activities such as dancing grass dragons and building stupas in some places. In addition to moon cakes, all kinds of seasonal fresh fruits and dried fruits are also delicious in the Mid-Autumn Festival. Another explanation for the origin of Mid-Autumn Festival is that the 15th day of the eighth lunar month happens to be the time when rice is ripe, and all families worship the land god. Mid-Autumn Festival may be the legacy of Qiubao.