Abstract: OBJECTIVE To study the relationship between genital tract group B Streptococcus（GBS） infection of pregnant women and premature rupture of membranes（PROM） and its influence on connexin 43（Cx43）, B cell lymphoma/lewkmia-2（Bcl-2） and Bcl-2 associated X protein（Bax） in membrane tissues. METHODS From Dec. 2018 to Dec. 2020, 91 pregnant women with PROM and 90 healthy pregnant women admitted to the Department of Obstetrics and Gynecology of Zhongda Hospital Southeast University were selected as PROM group and control group, respectively. The GBS infection of genital tract and the positive rate of Cx43, Bcl-2 and Bax protein in fetal membrane tissues were analyzed. RESULTS The GBS infection rate in the PROM group and the control group were 53.85% and 25.56%, respectively, and the difference was significant（P＜0.05）. The positive rate of Cx43 and Bcl-2 protein in the PROM group were significantly lower than those in the control group, while the positive rate of Bax protein in PROM group was higher than those in control group（P＜0.05）. The positive rates of Cx43 protein and Bcl-2 protein in GBS positive group of PROM group were significantly lower than those in negative group, while the positive rate of Bax protein was significantly higher than that in negative group（P＜0.05）. CONCLUSION Genital tract GBS infection of pregnant women was an important risk factor for PROM, and its mechanism might be related to the abnormal protein expression of Cx43, Bcl-2 and Bax in fetal membrane tissues.