Abstract: Objective To investigate the relationship between microRNA-29b (miR-29b) and vascular endothelial growth factor A (VEGF-A),and their effects on the occurrence and development of preeclampsia. Methods From September 2018 to January 2019,we collected placentas from 22 cases of early onset preeclampsia (EOPE),18 cases of late onset preeclampsia (LOPE) admitted to the department of critical care obstetrics,Anhui Provincial Maternal and Child Health Hospital.Another 20 cases of normal pregnant women delivered in our hospital served as control group.The expression of miR-29b in placenta was detected by RT-qPCR,and the expression of VEGF-A protein in placenta was detected by immunohistochemistry,the relationship between miR-29b and VEGF-A and their effects on the course of this disease were analyzed. Results Compared with the control group,the expression of miR-29b in the placenta of patients in the early-onset preeclampsia group and late-onset preeclampsia group was significantly higher (3.72±0.56 and 2.41±0.40 vs 1.46±0.47,P<0.05,respectively),while and the expression of VEGF-A protein was significantly lower (0.29±0.02 and 0.49±0.03 vs 0.74±0.05,P<0.05,respectively).Compared with the late-onset preeclampsia group (2.41±0.40),the expression of miRNA-29b in early-onset preeclampsia group (3.72±0.56) was significantly higher (P=0.001),while the expression of VEGF-A (0.29±0.02) was significantly lower (P<0.05).There was a negative correlation between the expression of miR-29b and the expression of VEGF-A protein in preeclampsia patients (r=-0.691,P=0.00).The expression of miR-29b in the placenta was positively correlated with the severity of preeclampsia,and negatively correlated with the gestational age (all P<0.05).However,the expression of VEGF-A protein in the placenta was negatively correlated with the severity of preeclampsia,and positively correlated with the gestational age (P<0.05). Conclusion Increased miR-29b in preeclampsia patients leads to decreased expression of vascular endothelial growth factor,which might affect the development of preeclampsia.