Utilizing the FVCOM-SWAVE wave-current coupling model, we numerically simulated the hydrodynamic characteristics of the Hangzhou Bay - Zhoushan sea area under the influence of Typhoon No. 2106 "In-fa". The results indicate that the astronomical tidal current field in this region exhibits typical semi-diurnal tide characteristics. The water flow in the Hangzhou Bay-Zhoushan sea area primarily consists of reciprocating flows in a northwest to southeast direction, reaching velocities of up to 2.5 m/s during spring tides. The superposition of Typhoon "Fireworks" and astronomical tides resulted in coastal and port areas facing the threat of storm surge, with Daxie Port experiencing a significant increase in water levels, reaching up to 138 cm. Extreme waves had a substantial impact on Hangzhou Bay and the Zhoushan sea area; however, Daxie Port is protected by island barriers, which mitigated the overall wave impact. Before and after the typhoon's landfall, the flow field in Hangzhou Bay underwent dramatic changes, forming vortices and increasing velocity. In contrast, Daxie Port was mainly affected by tidal currents, necessitating vigilance regarding erosion and local vortex-induced scour on the harbor seabed. This study provides crucial hydrodynamic environment references for sediment deposition and disaster prevention and mitigation in Daxie Port of Zhoushan.