Dougong is a unique part of ancient architecture in China with a very long history. From the architectural patterns on mulberry picking and hunting pots in the Warring States period more than two thousand years ago, as well as the tombs and murals preserved in the Han Dynasty, we can see the image of early fighting arches. There are many kinds of bucket arches with complex shapes. According to the use position, it can be divided into inner eaves bucket arch, outer eaves bucket arch and flat seat bucket arch. In cornice bucket arch, it can be divided into stigma bucket arch (used in the position of stigma), angle bucket arch (used in the corner of hall) and flat-headed arch. Bucket arch plays a very important role in ancient Chinese architecture, mainly in three aspects: first, it is located between columns and beams, and the load from the roof and superstructure will pass through the bucket arch to the columns and then to the foundation, so it plays the role of connecting the preceding with the following and transferring the load. Second, we can pick out the outermost truss sandalwood at a certain distance, so that the eaves of the building are more profound and the shape is more beautiful and spectacular. Third, exquisite structure and beautiful shape, such as bonsai, flower orchid, etc., are also good decorative components.