Mooncake (yuè bĭng) is a Chinese bakery product traditionally eaten during the Mid-Autumn Festival (Zhongqiu). The festival is for lunar worship and moon watching, when mooncakes are regarded as an indispensable delicacy. Mooncakes are offered between friends or on family gatherings while celebrating the festival. The Mid-Autumn Festival is one of the four most important Chinese festivals.

Typical mooncakes are round or rectangular pastries, measuring about 10 cm in diameter and 4–5 cm thick. This is the Cantonese mooncake, eaten in Southern China in Guangdong, Hong Kong, and Macau. A rich thick filling usually made from red bean or lotus seed paste is surrounded by a thin (2–3 mm) crust and may contain yolks from salted duck eggs. Mooncakes are usually eaten in small wedges accompanied by Chinese tea. Today, it is customary for businessmen and families to present them to their clients or relatives as presents, helping to fuel a demand for high-end mooncake styles. The caloric content of a mooncake is approximately 1,000 calories (for a cake measuring 10 cm (3.9 in)), but energy content varies with filling and size.

The tradition of eating moon-cakes on this festival has a long history in China, yet there are different versions of statements about its origin.

The most common version is that during the reign of Emperor Taizong of the Tang Dynasty, Taizong ordered his ablest general Li Jing to go for a battle against the Turkic clan in north ancient China to suppress their frequent invasions. The 15th day of the 8th month was exactly the day for the general's triumphant return. In order to celebrate his victory, fireworks were set off and music was played in and out of Chang'an City (the capital of the Tang dynasty), and citizens were happily enjoying a riotous night together with warriors. At that time, a business man, coming from the Tubo Kingdom (the ancient name for Tibet), presented Taizong with a kind of round cakes to celebrate Tang's victory.

Taizong gladly received the magnificently-decorated boxes and took the multi-colored round cakes out of the boxes and handed them out to his officials and generals. From then on, the tradition of eating round moon-cakes on the Mid-Autumn Festival was formed.