Abstract: As the mainstream solar cell product in the current PV market,the stability and improvement of the yield of PERC solar cells have been highly valued by solar cell manufacturers. This paper analyzes the various stages of the quartz boat used in the annealing process and provides improvement measures to investigate the abnormal proportion of PERC solar cells with EL quartz boat card groove marks in the annealing process during EL detection. The analysis results show that the main reason for the abnormal proportion of solar cells with EL quartz boat card groove marks in the annealing process is the exhaust backflow pollution during the low-pressure quartz boat saturation process and low-pressure annealing process. By adopting measures such as optimizing the setting of variable frequency vacuum pumps and installing one-way valves,the problem of exhaust backflow in the annealing process has been improved. The monthly average proportion of solar cells with EL quartz boat card groove marks in the annealing process on the production line has been reduced from 0.667% to 1.260% to 0.205%,effectively improving the yield of PERC solar cells. To provide new ideas and directions for the PV industry to improve the EL quartz boat card groove marks in the annealing process.