This article proposes a power plant system that integrates offshore wind and marine current energy. In response to the problems of low energy density, low energy utilization efficiency, large fluctuations in energy output, and high space occupancy in a single offshore wind and marine current energy source, a DC collection and AC grid connection system for wind turbine (WT) and marine current turbine (MCT) generator fields is proposed. Based on the characteristics of wind and marine current power generation, the topology diagram of the power generation system was analyzed, and mathematical models including wind turbines, marine current turbines, permanent magnet synchronous generator (PMSG), and converter control units were established. The system modeling and simulation were completed in the environment of MATLAB/Simulink, and the results demonstrated the potential feasibility of the proposed system topology structure.