Firstly,on the basis of the mathematical model of hydrodynamic drive systems applied to wind turbines,the influences of main structural parameters on the performance of hydrodynamic speed regulating system applied to wind turbines are analyzed.Then,the input /output characteristics of hydrodynamic speed regulating system,as well as the speed range and efficiency of the whole system,are determined according to the mathematical model of hydrodynamic torque converter with adjustable guide vanes as well as the torque and energy balance equation of the drive system.Finally,the transmission efficiency of the system at various structural parameters is quantitatively analyzed.The results indicate that both the speed range and the efficiency of hydrodynamic speed regulating system are related to the parameters of planet gears and the effective cycle round diameter of hydrodynamic torque converter with adjustable guide vanes; and that,according to wind turbine s input speed,the structural parameters of hydrodynamic speed regulating system can be reasonably selected,which not only ensures the efficient operation of wind turbines but also improves the utilization rate of wind energy and reduces the cost of wind turbines.