The reason is that moon cakes can be used as offerings to worship the moon god. Sacrifice to the moon is a very ancient custom in our country. It is actually an activity of worship of the "Moon God" by the ancients. Since its development, eating moon cakes and admiring the moon during the Mid-Autumn Festival have become essential customs for celebrating the Mid-Autumn Festival in various places in northern and southern China. Moon cakes symbolize reunion, and people regard them as festive food, using them to worship the moon and give them to relatives and friends.

Extended information:

Moon cakes symbolize reunion and should have been recorded in writing since the Ming Dynasty. If we look at the information about moon cakes and Mid-Autumn Festival folk customs from the Ming Dynasty, we should be able to see the historical trajectory of moon cakes meaning reunion: after worshiping the moon during the Mid-Autumn Festival, the whole family would sit around and share the moon cakes and fruits. Because mooncakes are also round, they are eaten by the whole family;

So the mooncakes gradually came to represent family reunion. In some places in Guangdong, there is a custom of worshiping the moon during the Mid-Autumn Festival, mainly for women and children. There is a common saying that "men do not worship the full moon, women do not worship the stove". Folk customs during the Mid-Autumn Festival in areas south of the Yangtze River are also diverse. Nanjing people love to eat mooncakes during the Mid-Autumn Festival, and they must also eat Jinling's famous dish of osmanthus duck with dancing fire dragon. During the Mid-Autumn Festival, people in Sichuan Province not only eat moon cakes, but also make glutinous rice cakes, kill ducks, and eat sesame cakes, honey cakes, etc.