Abstract: For the optimal design of wind power collection system for offshore wind farms, only reasonable configuration of the cable and switch is considered in most of existing design methods, and the impact of obstacle area on topology design is not analyzed. In this paper, a concrete topology optimization method of wind power collection system for offshore wind farms is presented by considering the effects of obstacle area. The geographic information system technology is used to process figures of the obstacle area, and the obstacle area is described as the minimum area rectangle encasing box by using minimal area encasing box method. On this basis, the optimization algorithm combining the advantage of Dijkstra algorithm and Prim algorithm is used to gain the obstacle avoidance path. Then a fuzzy comprehensive evaluation model based on the analytic hierarchy process (AHP), in which the economic and reliability factors are considered, is constructed to compare the performance of the different topologies. In the end, the optimal topology design of wind power collection system for offshore wind farms can be obtained. Case studies demonstrate the feasibility of the proposed algorithm.