【S】Objective:To discuss the application of four-dimensional ultrasound spatio-temporal correlation imaging (STIC) in the diagnosis of fetal ventricular septal defect (VSD) in early middle pregnancy. Methods: 148 suspected VSD fetus were selected from January 2015 to January 2018 in our Hospital, all pregnant women were given conventional two-dimensional ultrasound and four-dimensional ultrasound STIC examination in the early stage of middle pregnancy, the postpartum pathology or ultrasound as control, analyzed the diagnostic value of different methods on fetal VSD. Results: The results of postpartum pathology or ultrasound showed that, there were 50 cases (33.78%) of VSD fetus in 148 fetuses. The sensitivity, specificity, accuracy in the diagnosis of fetal VSD, the two-dimensional ultrasound were 96%, 97.56%, 97.30% respectively, the two-dimensional ultrasound combined four-dimensional ultrasound STIC were 96%, 97.56%, 97.30% respectively, the two-dimensional ultrasound combined four-dimensional ultrasound STIC were significantly higher than that of the two-dimensional ultrasound, the difference was statistically significant (P<0.05). Conclusions: The four-dimensional ultrasound STIC technology in early pregnancy can provide more diagnostic information for fetal VSD and improve the diagnostic efficiency of two-dimensional ultrasound for fetal VSD,it’s worth for further clinical promotion.