The principle of detecting continuous wave laser based on Fabry-Perrot etalon is introduced. Temporal coherence detection technology is applied to discriminate continuous wave laser from background noises and from other non continuous spectrum. The receiving principle of modulating laser source temporal coherence, the property of modulation, the technique structure and the EO information process are put forward, the features of low-high frequencies modulation and the key technology to make continuous wave laser coherent detection are described. Lastly, the development trend and feasibility of laser detection technology are predicted.