Laser warning system is a type of detection device which is used to capture,measure,identify incoming enemy laser signal. In the modern battlefield,accurate identification of incoming laser′s wavelength and incident angle can improve the army′s survival ability. To obtain the information of incoming laser′s wavelength and angle,a laser warning system based on digital signal processor and field programmable gate array was designed with the grating diffraction theory,and the incoming laser can be accurately identified by using specific image processing algorithm. Several tests have verified that the system can detect the incoming laser effectively and calculate the wavelength and azimuth of laser accurately. The wavelength range of the detected laser is from 800 nm to 1500 nm,and the accuracy is less than 10 nm,and the angular resolution is less than 2°.