In view of the problem that the photoelectric conversion efficiency of P-type passivated emitter rear contact (PERC) solar cells reduces due to the influence of potential induced degradation and damp-heat degradation during the service period, the degraded solar cells were recovered by photo & electric injection and thermal annealing process. In the meantime, the efficiency improvement mechanism was studied. The experimental results show that 94.32% of degraded solar cells are recovered successfully, and the average photoelectric conversion efficiency of all investigated cells is increased by 8.96%, under the optimal experimental conditions of 3 times standard sunlight intensity, 10 A of electric injection current, 150 ℃ of annealing temperature, and 50 min of processing. The results of photoluminescence spectra and quantum efficiency show that the photoelectric injection and thermal annealing can effectively reduce the internal and rear surface defects of silicon substrate caused by potential induced degradation and damp-heat degradation, and the photoelectric conversion efficiency of degraded solar cells can be finally improved.