The realization mechanism of wind power active control with grid disturbance is analyzed.Based on the principle of maximizing the use of existing pitch control actuator and software，a variable pitch control strategy supporting for system protection and frequency-controlled regulation is designed，as well as the integrating with the existing variable pitch system.Specially，an improved finite state machine of pitch control with grid disturbance supporting is proposed and is realized by dividing the control tasks into two modes:normal condition and grid disturbance condition.Moreover，a pitch control algorithm based on numerical calculation is developed to calculate reference pitch angle.The testing results show that the improved finite state machine is reliable，and the new pitch control strategy can meet the demands of system protection and frequency-control by continuously and greatly adjusting the output of wind turbines.