Due to the large number of parameter variables of the detailed model for the wind turbine pitch drive system to effect the simulation speed of the wind turbine, while the conventional first-order simplified model could not reflect the dynamic characteristics properly, based on the transfer function method, this paper proposes an improved simplified transfer function model considering both properties and parameters. Firstly, this paper describes the basic principle and structure of electric pitch system, and a detailed dynamic mathematical model of rotor flux orientation based on squirrel cage induction motor is established. Secondly, based on the transfer function method, the speed loop and torque loop are simplified, an improved simplified model considering the dynamic characteristics of pitch system is deduced and compares its frequency characteristics. Finally, this paper establishes a detailed, simplified and improved simplified pitch system model, and compares the pitch angle tracking characteristics and anti-load capacity of the different model, and then establishes the pitch drive system experimental platform to verify. The results show that the improved simplified model has the characteristics of considering both the dynamic characteristics of detailed model and less parameters of conventional simplified model, and different models should be applied to different situations