The automobile collision-proof one-dimensional scanning lidar system includes casing, laser, polarizing spectroscope, optical beam expander, quarter wave plate, reflector, one-dimensional scanning vibration mirror, light detector, amplifier, signal processing system, display and warning system and brake system. The present invention has low cost, small size, easy installation, high scanning frequency, precise detection of obstacle direction and long detection distance, and possesses functions of target distinction, ranging, measuring speed, intelligently keeping away from obstacle, etc. to prevent collision to various kinds of obstacle.