Abstract: OBJECTIVE To investigate the effect of delivery mode on hepatitis B virus(HBV) mother-to-child vertical transmission, so as to provide reference for control of HBV vertical transmission form mother to child. METHODS A total of 300 pregnant women with positive hepatitis B surface antigens (HBsAg)and their alive newborns delivered in our hospital from Jan. to Dec. of 2015 were selected, and the woman were divided into two groups as their actual delivery ways, including vaginal delivery group(194 cases) and cesarean section group(106 cases).The serum HBV markers and HBV-DNA levels were detected from pregnant women and newborn, and newborns given injection Hepatitis B vaccine and Hepatitis B hyper-immune globulin, observing the mother-to-child vertical transmission within 24 h and 6 months after delivery. RESULTS The positive rate of HBsA, HBsAb and HBV-DNA in newborn babies after delivery 24h and 6 months, had no significant difference between the two groups; when mother from vaginal delivery group with HBV-DNA＞106copies/ml, the positive rates of HBsAg in babies after delivery 24h and 6 months were 54.55% and 25.00%, positive rates of HBsAb were 6.82% and 90.91%, and positive rates of HBV-DNA were 60.23% and 22.73%, and for cesarean section group were 36.54% and 9.62%, 5.77% and 96.15%, 40.38% and 7.69%, respectively. The vaginal delivery group had higher HBsAg and HBV-DNA positive rates than the cesarean section group in different times (P<0.05),and HBsAb positive rates were no significant difference between the two groups. CONCLUSION When HBV - DNA at low level, delivery way has no obvious effect to mother-to-child HBV vertical transmission; when HBV - DNA at high level, vaginal delivery are more likely to have mother-to-child HBV vertical transmission, suggesting to take cesarean section delivery when HBV DNA is high.