Abstract: This paper presents a new measurement method of power angle based on Two Way Automatic Communication System (TWACS) technology. In the substation, the voltage distortion signal is modulated in the vicinity of the voltage zero crossing point by the artificial short\|circuit in the secondary side of the transformer. Due to almost no transmission delay of distortion signal, it is extracted in the low\|voltage side and analyzed with time\|frequency analysis technology. Then the time distribution of the energy parameters is used to determine the voltage zero\|crossing time difference between the initial end and terminal of the power line. Finally, the power angle is calculated according to the transformer connection group. Example results show that the proposed method is simple and the accuracy can meet the requirements of the distribution network stable monitoring.