To explore the influence of pregnancy and delivery and associated with obstetric factors on female postpartum stress urinary incontinence. Methods：Perineum ultrasound imaging technology was applied to measure bladder neck mobility and urethral rotation angle. The occurrence of stress urinary incontinence after vaginal delivery, Logistic multi-factors analysis of pregnancy and maternity related factors on the impact of stress urinary incontinence. Results:135 cases with 70 cases of vaginal delivery group and 65 examples maternal cesarean delivery group respectively, there is no significant difference between the age, birth gestational age and fetal weight and BMI between the two groups(P > 0.05). the incidence of SUI in natural birth group was 25.7% and 10.8% in the group of cesarean sections, the difference is statistically different (χ2 = 4.989, P = 4.989). At 6 week,10 week and 15 weeks after postpartum, bladder neck mobility and urethral rotation angle in vaginal delivery group was higher than cesarean delivery group, the difference is statistically different(P<0.05). Logistic regression analysis showed that vaginal delivery, prenatal SUI, forceps midwifery, perineum tear, urgent production history, drinking alcohol, estrogen therapy, uterine prolapse ARE risk factors associated with postpartum SUI. Vaginal delivery (OR = 3.215, P = 3.215), uterine prolapse (OR = 4.013, P = 4.013) were independent risk factors associated with postpartum SUI. Conclusion: Compared with cesarean delivery, vaginal delivery can increase the rates of SUI, vaginal delivery and uterine prolapse were independent risk factors associated with postpartum SUI.