In order to solve the disadvantages of slow response and large control error about wind farm power control system , an improved PID algorithm wind farm power control system was proposed. Firstly, a large amount of data from the actual operation of wind farm SCADA system was collected, identification tool was used to do the model identification, the transfer function was obtained based on the least squares solution algorithm. Secondly, The Matlab test model was builted , ideal performance of PID controller was concluded by using the proportional and differential advanced and integral behind control. Finally, the simulation parameters were used in the practical wind farm power control system. Results shows the actual application value is larger and it has fast response speed and high control precision.