Abstract: Objective To dynamically observe the shape of levator hiatus and the mobility of bladder neck with three dimensional transperineal ultrasound, and then to evaluate female pelvic floor in early postpartum after delivery. Methods 170 primiparae (the vaginal delivery group and the cesarean section group) and 35 nulliparous women were recruited, and three dimensional transperineal ultrasound were performed with standardized gynecological pelvic settings. Ultrasonic dynamic imaging information was obtained in the condition of resting, Valsalva maneuver and anal sphincter contraction, including two-dimensional midsagittal view and the three-dimensional axial plane in which some biometric measurements were determined. Results The anteroposterior diameters of levator hiatus were significantly greater on sphincter contraction in the vaginal delivery group than that in nulliparous group after the 6-8 weeks delivery, but the measurements of the levator hiatus within cesarean delivery group and nulliparous group did not show statistically significant differences ( P>0.05). The mobility of bladder neck was significantly greater on Valsalva maneuver in the vaginal delivery group than those in the other groups, while the backward motion of bladder neck was greater on Valsalva maneuver in the cesarean section group than that in nulliparous group. The incidence of postpartum stress urinary incontinence was greater in the vaginal delivery group (10/104) than that in the cesarean section group (4.5%,3/66), but no statistically significant differences were observed ( P>0.05). 　　Conclusion The large difference of pelvic floor exists between vaginal delivery and cesarean delivery. The bladder neck decent and levator hiatus anteroposterior diameter may be relatively sensitive indicators in ultrasonic evaluation of pelvic floor muscle contraction, especially the latter may be adopted as an observation index to evaluate pelvic floor muscle recovery after delivery.