Abstract: The co-simulation of multiple simulation software is used to carry out the related research of wind turbine, which can give full play to the advantages of simulation software and make up for the shortcomings of a single simulation software in complex simulation scenarios and model construction. For the problem of too long simulation time caused by small simulation step size in GH Bladed and Matlab co-simulation, the overall design of the co-simulation is first carried out, and a simplified model is built in Matlab through reasonable simplification, which enhances the speed of the co-simulation. Then, in order to analyze and evaluate the influence of different simulation steps on simulation results, generator power, rotational speed, high and low speed shaft load and their equivalent fatigue load, as well as simulation duration are selected as the evaluation indicators and a quantitative evaluation method is proposed to consider both simulation accuracy and simulation time. Finally, the built co-simulation platform is used for co-simulation of different simulation steps under various working conditions and the simulation results are processed and analyzed. The simulation steps under different working conditions can be taken into account both simulation accuracy and time length, which provides a reference for the selection of simulation steps in co-simulation.