Optical fiber composite overhead ground wire (OPGW) has been rapidly developed and applied in the intelligent monitoring of power system with its unique superiority. In this paper, a new method of optical fiber sensor lightning signal waveform is studied, which is based on the new method of OPGW polarization state. Firstly, the ATP-EMTP software is used to establish the transmission line model simulation to get the electric data when the lightning strikes OPGW, then, based on the Faraday magneto optic effect principle, the electrical signal is converted into the optical polarization signal in the OPGW internal optical fiber, and this method can get better OPGW optical sensing transmission line lightning waveform, and the accuracy of the simulation results is verified by the data of OPGW lightning location system installed on the actual transmission line. The results show that the lightning current waveform of OPGW optical transmission line is greatly affected by lightning current and is different from the traditional current traveling wave.