【Abstract】 Objective To investigate the analgesic effect of nerve block located under nerve stimulator and its effect on the expression of oxygen free radical in total knee arthroplasty (TKA). Methods 80 patients treated with total knee arthroplasty in March 2016 2017 year in March in our hospital, according to the different choice of anesthesia, were divided into observation group and control group. The observation group was treated by nerve stimulator under nerve block. The control group was treated with general anesthesia. The pain and joint function of oxidative stress levels were observed. Results There was no statistically significant difference of preoperative mechanical pain threshold between the two groups. The mechanical threshold values 6, 12, 24, 48 h after operation were higher than those before operation. MDA and AOPP after operation of observation group were lower than that of control group. The urinary retention, nausea, vomiting and hypoxemia of observation group were lower than that of control group. Lysholm score of observation group was significantly higher than that of control group. Conclusion Nerve block under the nerve stimulator can improve the effect of labor and reduce the inflammatory reaction in total knee arthroplasty patients.