Abstract: An active laser-illuminating sniper detector based on cat eye effect is developed. According to actual circumstances, some tests were conducted to verify the detection performance of the detector. Testing results show that night-vision sight and telescope sights with objective aperture diameters of 32mm, 40mm, 42mm and 50mm can be effectively detected by the detector in the range of 20m to 200m, and thermal weapon sight can not be detected either.