Objective To investigate the effects of perinatal maternal infection of hepatitis B virus on neonatal umbilical cord blood immune factor and lymphocyte subsets,and to provide a theoretical basis for the prevention of neonatal hepatitis B.Methods A total of 110 cases of neonatus in Pengzhou People's Hospital from June 2015 to June 2016 were selected and divided into the observation group and the control group according to whether the pregnant women were infected with hepatitis B virus in perinatal period or not,each group had 55 cases.Neonatus umbilical cord blood were taken to detected serum immune globulin A (IgA),G(IgG),M(IgM) and lymphocyte subsets CD3+,CD4+,CD8+,CD19+,and the two groups' neonatal hepatitis B infection,lung infection,the incidence of jaundice and survival were compared.Results The observation group's neonatal IgA and IgM were respectively(0.46±0.12) and (0.68±0.23)g/L,which were significantly higher than those of the control group[(0.21±0.08),(0.68 ± 0.23)g/L],the differences had statistical significance(P＜0.05).There were no statistical significance in IgG level between the two groups(P＞0.05).The observation group's CD4+/CD8+,CD3+,CD4+ were significantly higher than those of the control group,CD19+ was significantly lower than that of the control group,the differences had statistical significance (P＜ 0.05).There was no statistical significance in CD8+ (P＞0.05).The observation group's neonatus survival rate was 96.36 ％,which was lower than that of the control group(100.00 ％),but the difference had no statistical significance(P＞0.05).The observation group's hepatitis B infection rate,pulmonary infection rate,incidence of jaundice were 41.82 ％,29.10 ％,10.10 ％,which were significantly higher than those of the control group(9.10 ％,7.27 ％,0.00 ％),the difference had statistical significance(P＜0.05).Conclusion Perinatal pregnant women infected with hepatitis B virus could sharply increase the level of IgA and IgG,increase the CD3+,CD4+,CD4+/CD8+,reduce the proportion of CD19+,affect neonatus immune function,and are more susceptible to viral infection.