Abstract: To scientifically assess the impact of oil spill accidents in port areas, taking the spill accident in the navigation channel of Zhapu Port area of Jiaxing Port as an example, the MIKE21 software was applied. Based on the Lagrangian "oil particle" theory and considering the different processes after the oil spills into the sea, a two-dimensional numerical model was constructed. The model incorporated 5,200 sets of continuous operating conditions to comprehensively cover the hydrological and meteorological conditions as well as oil spill scenarios in the area. The oil spill spreading situation within 72 hours was obtained, and the surrounding major sensitive target areas were divided into regions based on the results of oil spill risk index calculations. The research results indicate that continuous operating conditions are more geographically typical and non-random compared to random operating conditions. Under continuous operating conditions, the statistical area affected by oil spill spreading at sea reaches up to 2,547.0 km². The Jiulongshan important coastal tourist area, Haiyan agricultural and fishery area, and Hangzhou Bay wetland marine protected area are considered high-risk areas, significantly impacted by the oil film from the spill accident in the navigation channel of the area. The degree of impact on other sensitive targets varies with the distance of oil film spreading.