Wind turbines have become popular with the recent interest in renewable energy sources. And also Wind turbine is a mechanical device, which is used to convert Kinetic energy that extracted from wind into mechanical energy. The aerodynamic forces acting on the rotor blade is mainly the basis of energy conversion system. Wind turbine system is highly nonlinear system, unstable and complex involving some random (turbulence) wind speed. As a result, the output power from the system is fluctuated (varied) and also the mechanical part of the turbine become structurally overloaded as well as damage itself physically at random strong wind condition. The wind turbine is connected with Permanent magnet synchronous Generator (PMSG) because of its most reliable and efficient wind generator. This generators used as a load which used to generate the electrical power. Then, the pitch control system is one of the most widely used control techniques to regulate (control) the output power and also, to maintain (protect) the mechanical part of the wind turbine. In This thesis Supper Twisting Sliding Mode Controller for pitch angle control with PMSG based Horizontal-axis variable speed wind turbine system is described. The controller is designed to track and regulate (limit) the mechanical rotor speed and the mechanical power that extracted from the wind turbine by adjusting the pitch angle under variable wind condition. Thus, to improve the performance of the WT system, a robust variable structure controller will be applied. The mathematical model of the system has analyzed and presented in detail. Finally, the simulation result has done for 1.5MW generated power and 1.811 rad/sec mechanical speed using mat lab tm/Simulink. The MATLAB simulation results show that the performance of the proposed controller was better than the conventional PID controller and SMC controller based on the result analysis table 4.1 and in figure 4.2 shown. Keywords: HAVSWT, Pitch angle, Drive train, PMSG, PID, SMC, and STA_SMC.