In order to improve the accuracy and reliability of the phase laser ranging system,a new type of phase laser ranging system which contains two almost identical receiving circuits and the transmission was designed. The system achieves high accurate measurement in some particular environments through the use of low jitter,small frequency difference clock generation technology and phase-shift measurement technology. The system is mainly composed of cascaded PLL programmable modulation signal generating,laser emission and receiving module,the automatic gain control,mixing filtering and data acquisition. Modulated signal is generated by the clock source,and the feedback signal and received signal are amplified,and then the collected data are processed and analyzed. Modulator and transmitter circuits of the system are optimized in the design of circuit. Pigtailed laser with low return loss and simple practical automatic gain module are used. The experimental results show that the phase laser ranging system circuit is simple and practical,and has high stability and high precision.