To solve the problem of low spatial resolution of remote target detection caused by fixed angle resolu-tion scanning of traditional multi-line lidar,an eight-line lidar scanning system with symmetrical arrangement of two light sources is proposed.The parameters of the rotating mirror and light source and the scanning trajectory of the beam are studied using the ray vector method,and the parameters of the eight-line lidar are optimized by combining the lidar equation.By strictly calculating the beam trajectories scanned by the mirror with different inclination angles,two light sources are symmetrically arranged on both sides of the eight-sided mirror for time-sharing luminescence detection to realize the eight-sided mirror rotation scanning system with high spatial resolution.The vector calcula-tion results show that there are two scanning detection beams in front of the human body at a distance of 100 m,and there are still three scanning detection beams in the side and edge of the human body,indicating that the proposed eight-sided mirror rotating scanning system can detect long-distance targets more effectively using scanning beams,which is better than the Velodyne 64-line lidar.