Abstract: Some old oil fields in the eastern South China Sea are gradually entering the late stage of development and production, and there is an urgent need to implement adjustment wells to ensure production replacement. Multi-branch horizontal wells can effectively increase the oil drainage area of the reservoir, achieve one well with multiple holes, and are the main well type and important means of adjusting wells to tap potential. By studying on-site drilling cases of small wellbore multi-branch horizontal wells, this paper summarizes the difficulties of suspended sidetracking technology in small wellbore multi-branch horizontal wells and the technical characteristics of using pushing and leaning rotary directional drilling tools for lateral drilling. Specific empirical values of engineering parameters such as trajectory reservation, lateral drilling safety distance, and wall thickness are provided, in order to provide reference experience and technical reference for subsequent similar branch well operations in the eastern South China Sea.