A supervisory control and data acquisition system is designed for wind farms, including the local controller and remote monitoring terminal. The data of the sensors collected by the lower-computer is transmitted to the host computer monitor terminal through the GPRS wireless network after preliminary treatment. In the host computer, the data is processed and displayed by the virtual instrument. The remote monitoring terminal can also send commands to control the actuators in the wind farm. Wavelet de-noising principle is used to process the data collected, improving the reliability and stability of the system.