The Yangshan Sea Area is a macrotidal multi-channel system jointly governed by astronomical tides, East Asian monsoon and Yangtze River runoff, which induces remarkable seasonal evolution of residual currents . At present, the coupling effects and relative contributions of the three hydrodynamic drivers remain insufficiently quantified, and the spatial differentiation of dynamic responses among different channels is still unclear. Based on a high-resolution three-dimensional FVCOM hydrodynamic model, combined with multiple controlled numerical experiments and a differential decomposition method, this paper investigates the seasonal variation characteristics of residual currents in Yangshan waters and quantitatively distinguishes the independent driving effects of tides, wind stress and runoff.