Abstract: Objective To investigate the application value of pelvic floor ultrasound to observe the structure changes of anterior compartment in primipara with postpartum stress urinary incontinence. Methods Transperineal pelvic floor ultrasound was performed on a random sample of 182 primiparas in 6 to 8 weeks after vaginal delivery,who were divided into SUI group(72 cases) and control group(110 cases). The structure changes of ultrasonic images of anterior compartment were observed at rest state and on maximal Valsalva maneuver. The observation and measurement parameters include:bladder neck-symphysis pubis distance(BSD),detrusor wall thickness(DWT),retrovesical angle(RA) at rest state and bladder neck descent(BND),urethral rotation,urethral mouth funnel formation,bladder prolapse on maximal Valsalva maneuver. Results The detrusor wall thickness of SUI group was(3. 21 ±0. 86) mm,and that of control group was(3. 11 ±0. 76) mm. It showed no statistical difference at rest state(t=0. 798,P=0. 426). The position of bladder neck of SUI group was lower[(23. 61 ±4. 57) mm vs.(25. 35 ±4. 05) mm],and RA was greater than control group[(134. 14 ±21. 04) ° vs.(114. 29 ±10. 53) °]. There was a statistically significant change(t value was- 2. 697 and8. 422,P value was 0. 008 and 0. 000 respectively). BND[(30. 39 ±8. 37) mm vs.(21. 82 ±7. 65) mm] and urethral rotation[(45. 21 ±12. 78) ° vs.(33. 25 ±14. 58) °]of SUI group was also greater than that of control group on maximal Valsalva maneuver. There was significant difference(t value was 7. 115 and 5. 673 respectively,P value was 0. 000). The urethral mouth funnel formation rate(55. 56% vs. 27. 27%) and bladder prolapse formation rate(63. 89% vs.24. 55%) of SUI group were significantly higher than that of control group(χ2value was 11. 831 and 28. 041,P value was0. 001 and 0. 000 respectively). Conclusion The occurrence of postpartum stress urinary incontinence has a significant relation to the impairment of supporting structure of bladder neck,urethra and levatorani. The changes of structure and function of anterior compartment can be observed by pelvic floor ultrasound. Abnormal changes of pelvic floor can be detected early. It can provide the objective basis for the clinical diagnosis and treatment of postpartum stress urinary incontinence.