In order to investigate the output variation of the silicon solar cell under the solar simulator and its internal carrier transport properties, light soaking in situ of crystalline silicon solar cell technology was conducted before the standard test which measures the cell's current-voltage characteristics, spectral response and other parameters. The results show that the attenuation of current-voltage characteristics results in reduced efficiency. The short wavelength spectral response of solar cell is decreased slightly after light soaking in situ. The reason is that the surface of the cell generates a very small amount of defect during the light soaking process whichleads to slight decrease of the carrier recombination. The significant decrease of the spectral response during the long wavelength is due to a large number of the bulk defects being activated, which results in the long-wave carrier recombination when it passes through the silicon.The solar cell was then annealed and tested after light soaking. The results show that annealing has a good effect on the recovery of bulk defect deep inside the cell. There is a partial recovery of bulk defects after annealing while the surface defects are not recovered, which leads to the incomplete recovery of current-voltage characteristics and spectral response.