In order to discuss the application of sensorless diagnosis in the fault diagnosis of wind power generator. A method which is different from the traditional model of wind turbine generator system is proposed. A simulation model of wind power generator is established based on MATLAB/SIMULINK, the dynamic simulation model of transmission gear in normal and fault condition is established based on ADAMS. Combining the two models, electromechanical simulation model is constructed based on ADAMS/MATLAB, and the simulation experiment is carried out. The stator current and voltage signals are simulated under normal and fault condition, in theory, the characteristics of current fault about normal gear or gear which there are broken teeth are studied. The simulation and experimental results show that the electromechanical combined simulation model can well reflect the operating conditions of the wind turbine under different conditions, which provides a new method of modeling and Simulation for the wind turbine fault diagnosis. At the same time, which shows that the method of stator current detection can be applied to the fault diagnosis of wind turbine.