Pseudo random code modulated laser ranging system could detect high frequency and low peak power by emitting high-order modulated laser, and achieve high signal-to-noise ratio by using high frequency detection and statistics. The system has the characteristics of small volume and light weight. It is a lidar system suitable for long distance. However, the measurement accuracy is related to the modulation frequency. In the past, high modulation frequency was usually used to achieve high-precision measurement. A laser radar prototype modulated by pseudo-random code was developed, which adopted 100 MHz modulation repetition rate, optical antenna with pupil diameter of 0.1 m. Through Gaussian statistics of the echo signal in the cycle, the high-precision ranging of 0.1 m was achieved in the laboratory environment when the signal-to-noise ratio was 5. Through theoretical and experimental analysis, it is proved that the measurement accuracy can be effectively improved by increasing the clock frequency and signal-to-noise ratio.