A fiber anemometer that used in wind velocity monitoring is introduced in this paper. FBG is used as a sensor device. Fiber anemometer uses wind-cup to modulate FBG’s wavelength, so that wavelength changing frequency stand out difference wind velocity. The system demodulate frequency is about 1KHz and its spectrum width is about 30-40nm, which means each channel has a capacity of accommodate 30-40 sensors. By wavelength division multiplexing (WDM) technology, this system is very suitable to be adopted in wind power generation in consideration of its large-capacity. Design scheme is described in detail. Some experimental data and equipment are also described in this paper.