Objective To explore the factors affecting muscle function of the pelvic floor in women after normal vaginal delivery and to provide reference for clinical intervention.Methods A total of 1,232 women after normal vaginal delivery were selected and their pelvic floor muscle function was assessed at 6-8 weeks postpartum using surface electromyography (sEMG), then their demographic and clinical data were retrospectively collected. Factors affecting the incidence of abnormal sEMG signal were analyzed.Results Abnormal sEMG signal was seen in 605 women (49.1%) in pre-testing resting stage, 839 women (68.1%) in fast twitch stage, 1,012 women (82.1%) in slow twitch stage, 1,029 women (83.5%) in endurance testing stage, and 443 women (36.0%) in post-testing resting stage.Prolonged first stage of labor was a risk factor for abnormal sEMG signal in the slow twitch stage （P＜0.05）, age of 30 years or older was a risk factor for abnormal sEMG signal in the endurance testing stage, childbirth expe-rience was a protective factor in the fast twitch stage and endurance testing stage, epidural analgesia was a protective factor in the slow twitch, fast twitch and endurance testing stage （all P＜0.05）.Conclusion Epidural analgesia is a protective factor for pelvic floor muscle function in women after normal vaginal delivery in the early postpartum period.Age of 30 years or older and prolonged first stage of labor may increase the risk of pelvic floor muscle injury.Targeted nursing intervention could be taken according to women′s conditions to protect their muscle function of the pelvic floor.