Objective: To investigate the status of Streptococcus agalactiae（S.agalactiae）infection and drug resistance in Shanghai from 2015 to 2017. Methods: A retrospective analysis was performed on the positive rate of S.agalactiae in departments of obstetrics, gynecology and andrology at Shanghai First Maternal and Infant Hospital from 2015 to 2017, and antimicrobial susceptibility test was performed on 374 strains of S. agalactiae isolated in 2017. D-test was performed for strains resistant to erythromycin and susceptible to clindamycin. Results: In 2015, the positive rates of S.agalactiae at departments of obstetrics, gynecology and andrology were 2.69%（88/3 267）, 3.10%（101/3 255）, 5.93%（28/472）, respectively; in 2016 were 3.94%（378/9 578）, 3.42%（92/2 685）, 7.49%（14/187） respectively, and in 2017 were 3.90%（251/ 6 429）, 4.10%（110/2 682）, 7.22%（13/180）, respectively. The positive rates of S.agalactiae in department of obstetrics from 2015 to 2017 was 3.72% (717/19 274). In 2017, the resistance rates of S.agalactiae to erythromycin, clindamycin and levofloxacin were 63.37% (237/374), 53.48% (200/374) and 25.13% (94/374), respectively. None of the strains were found resistant to penicillin, ceftriaxone, linezolid and vancomycin. Conclusions: The infection of S.agalactiae has a trend of increasing from 2015 to 2017, which should be paid attention seriously. It is important to perform screening of S.agalactiae in pregnant women and non-pregnant adult patients. Penicillins are still the first choice for the treatment of S.agalactiae infection.