The 15th day of the 8th month of the Chinese lunisolar calendar is the traditional Mid Autumn Festival in China, also known as the Moon Festival. In 2010 the Mid-Autumn Festival falls on Wednesday, September 22nd, and in 2011 it falls on September 12th. See our special report on the Mid-Autumn Festival.

Why is the Mid-Autumn Festival so important? It is related to the moon and Chinese people like the moon very much. In Chinese culture, the full moon is a symbol of peace and prosperity for the whole family. Its roundness symbolizes wholeness and togetherness. In the middle of the eighth month of the Chinese calendar the moon is full, and eight is also a popular number in Chinese culture, symbolizing wealth and prosperity. So people believe this day is very propitious.
Celebration of the Mid-Autumn Festival
The Mid-Autumn Festival has a history of 2000 years. During these 2000 years lots of Mid-Autumn traditions have been thought up by Chinese people. All the celebrations show the happiness and excitement of people.

The main celebrations during the Mid-Autumn Festival are appreciating the moon, eating Autumn moon cakes together and making Chinese Mid-Autumn Festival lanterns. These three celebrations have been passed from generation to generation. Chinese people may think the Mid-Autumn Festival is not coming if they don’t do these three things.

In some places in China people celebrate the festival in different ways. In Chaozhou, Guangdong Province, people eat taro to celebrate the festival, because the taro harvest occurs at the same time as the festival. They eat taro and hope the harvest is good in the next year. In Nanjing, people cook duck with sweet-scented osmanthus, because Nanjing people think sweet-scented osmanthus is a symbol of peace. In some places people make fires inside a towers to celebrate the Festival Mooncake, because they think the fire is a symbol of good business.

Source : http://www.chinahighlights.com/travelguide/culture/mid-autumn-festival.htm