Abstract: Owing to the low accuracy of traditional method of measuring phase difference and complicated system structure, a new method based on uniform delay of standard frequency phase is proposed in this paper. The standard frequency signal and m-1 equal-delayed standard frequency signals within the zero-crossing interval of the measured signal are counted. The phase differences of the measured signal are obtained after average filtering. Analysis and calculation show that the error of this method is one mth of traditional method. In this method, system-on-a-programmable-chip (SOPC) is applied to design measurement system and phase difference measurement experiments are carried out. Results show that the measurement error is less than ±0.5° and precision is higher than 0.14% under the given conditions. When the standard frequency is increased and the uniform delay interval is reduced, measurement accuracy is further improved. It is concluded that this method has higher precision and better concertedness than traditional method.