Abstract: Most of the old oilfields in the eastern South China Sea are facing problems such as rapid production decline and insufficient platform slots. The development of old oilfields urgently requires old well sidetracking to enhance oil recovery. However, some old wells still have production potential during production, and conventional window sidetracking faces the problem of abandoning the original production capacity of old wells. To this end, the research on the integration of through-bore whipstock and directional perforation, as well as the technology of single-well dual-limb alternate production, has solved the problem of new and old wellbores rotating production and achieved the maximization of oil recovery in old oilfields. Through application, it has been proven that multi-branch well alternate production technology has the characteristics of short construction period and simple process, which has important guiding significance for tapping the potential of offshore old oilfields and efficient development of marginal oilfields.