A new design of a laser warning receiver is proposed. We use grating diffraction method to distinguish the incidence laser from background sun light. In this paper, the laser warning receiver is designed based on DSP. The principle of the instrument is introduced. The instrument consists of DSP peripheral module, signal sampling module and display module. The three modules circuits are described. The experiment result shows the maximum error of wavelength and azimuth of the laser warning receiver are 6.2 nm and 0.6??. It can real-time measure the laser wavelength resolution in 10 nm and azimuth resolution in 1??.