With the complex structure of distribution network, the efficiency of manual phase measurement is quite low. To reduce the time of interruption of power supply, a remote on-line phase measurement system is designed, and an assessment method for phase measurement operation is proposed. Firstly, collect secondary voltage of potential transformer or charged indicator; secondly, combine the voltage with time scale by phase measuring equipment witch is installed in DTU; and finally, transmit the voltage waveform to the main station over the distribution automation system to analyse whether the phase is the same. Based on the operating time and accuracy of the phase measurement system, the connection stability and phase measurement quality is analyzed by the main station. The results show that the remote on-line phase measurement system can obtain the phase difference in a short time, the result of phase measurement is stable and reliable, work efficiency has been significantly improved.