To improve the detection performance and location finding accuracy of the conventional sniper detection, an active laser detecting method was designed based on cat eye effect theory. The device takes a semiconductor laser as light source and a linear array CCD as laser echo detector. The specific reception field of view was matched with 2160 elements of linear CCD by using proper optics system, and its detection accuracy reached the level of mrad. Operation timer of CCD was created by FPGA and the program could be compiled on line and modified conveniently, which could improve the speed of design greatly. The system is simple and portable, and it has its own power management system. The detection distance reaches 250 meter after minimizing noise by frame-subtract and threshold comparing algorithm.