Objective To understand the serotype distribution and drug resistance genes of Streptococcus agalactis (group B streptococcus, GBS) isolated from the reproductive tract of pregnant women, and provide reference for the clinical prevention and treatment of GBS infection and rational use of antimicrobial agents. Methods Hospitalized women in late pregnancy with GBS detected in reproductive tract secretion from January 2020 to June 2021 were selected as research objects. Genotypes and drug resistance genes of isolated and cultured GBS were analyzed by polymerase chain reaction (PCR) and gene sequencing. Results A total of 62 GBS strains were isolated, serotypes of which were types Ⅲ (n=30, 48.4%), Ⅰa (n=16, 25.8%), Ⅰb (n=8, 12.9%), Ⅴ (n=6, 9.7%), and Ⅵ (n=2, 3.2%) respectively. GBS drug susceptibility test showed high resistance to tetracycline, erythromycin and clindamycin, with drug resistance rates of 77.4%, 71.0% and 67.7% respectively. There was no resistance to ampicillin, penicillin G, quinupristin/dalfopristin, linezolid, and vancomycin. The carrying rates of tetracycline resistance genes tetM, tetO and tetL in tetracycline resistant GBS strains were 75.0% (36/48), 33.3% (16/48) and 8.3% (4/48) respectively; carrying rates of erythromycin resistance genes ermB, mefA/E, ermA and ermTR were 72.7% (32/44), 22.7% (10/44), 18.2% (8/44) and 13.6% (6/44) respectively; carrying rate of clindamycin resistance gene linB was 42.9% (18/42). Erythromycin and clindamycin resistance phenotypes of GBS were mainly cMLSB (75.0%, 36/48), mostly mediated by ermB (44.4%, 16/36) and ermB+linB (27.8%, 10/36) genes. Conclusion Serotype Ⅲ is the most common GBS serotype in the reproductive tract of pregnant women. GBS is highly resistant to tetracycline, erythromycin and clindamycin. Tetracycline resistance is mainly mediated by tetM and tetO genes. Erythromycin resistance is mainly type cMLSB mediated by ermB gene, and clindamycin resistance is mainly mediated by linB gene.