ABSTRACT Objective To analyze the changes of pelvic floor structure in patients with stress urinary incontinence (SUI) in early stage of pregnancy. Establish the ultrasound diagnosis model of SUI based on discriminant analysis.Methods Select 115 female cases who had been given physical examination in early stage of postpartum at Affiliated Hospital of North China University of Technology from August 2017 to September 2019.They were randomly divided into the experimental group(98 training samples) and the test group (12 validation samples).The experimental group consisted of 52 SUI cases and 42 non-SUI cases. Pelvic floor ultrasound was examined on all of the cases and the value of HBL,BND,URA,PVUA1,PVUA were recorded. Analysis and compare the according data, use Fisher stepwise discriminant analysis method to establish the diagnosis model, validate the according model and use ROC curve to evaluate the model.Results (1)Value of HBL,BND,URA,PVUA1,PVUA2 in the SUI group were significantly higher than those in the non-SUI group (P< 0.05), the difference has statistic significance.It indicated that women with SUI in the early postpartum period have a lower bladder neck position.The mobility and rotation of bladder neck in tension state are greater.(2)Diagnostic model of SUI: group without SUI :Y0=-108.764+2.223X2+1.187X3+1.404X5;group with SUI:Y1=-144.728+4.145 X2+1.879 X3 +1.499X5.(Y0 represents the group without SUI, Y1 represents the group with SUI; X2 represents BND, X3 represents URA and X5 represents PVUA2). (3) The results was obtained by self-test and cross-validation in the experimental group with an accuracy of 94.9%and 93.9%.The results were checked in the test group with an accuracy of 82.3%.It shows that the diagnostic effect of the model is ideal. Throw evaluating ROC curve we get that the area in the curve is 0.939,it is further proved that the diagnosis value of the model is higher. Conclusion The multi-variable combined diagnostic model established by Fisher discriminat analysis pelvic floor ultrasound can objectively reflect the changes of pelvic floor function of SUI patients in the early stage of postpartum which provide evidence for early clinical diagnosis and intervention.