Abstract: Low permeability and ultra-low permeability oil and gas reservoir resources account for more than 90% of the total resources in the East China Sea. The effective development of low permeability and ultra-low permeability oil and gas fields is the main research direction in the East China Sea at present. The application of horizontal branch wells can effectively improve the single well productivity of conventional low permeability oil and gas fields. In the future, horizontal branch wells will be used to develop low permeability oil and gas fields on a large scale. Therefore, by analyzing the implementation of horizontal branch wells in the East China Sea and deeply summarizing the drilling technology of horizontal branch wells, we can not only improve the operation efficiency, but also provide reliable technical support for the vigorous development of oil and gas fields in the East China Sea. In this paper, the drilling technology of horizontal branch wells is deeply analyzed from the aspects of sidetracking tools, drill bits, suspended sidetracking technology and partition walls, etc. Combined with the actual drilling situation of horizontal branch wells in XX gas field in the East China Sea, it summarizes the key technology of horizontal branch wells in oil and gas fields of the East China Sea, which provides a lot of experience for the promotion and application of horizontal branch wells in the East China Sea in the future.