This study was aimed to describe the standardized treatment rate of syphilis-infected pregnant women in Hunan province and to explore the determinants for standardized treatment. All syphilis-infected pregnant women registered in the Information System of Prevention of Mother-to-Child Transmission of Syphilis Management (IPMTCT) in Hunan between January 2015 and December 2018 were included in this study. Among 9,059 pregnant women with syphilis, 7,797 received syphilis treatment, with a treatment rate of 86.1%, and 4,963 underwent standardized syphilis treatment, with an average standardized treatment rate of 54.8%. The facilitators for the standardized treatment included abnormal reproductive histories (aOR = 1.15, 95%CI:1.03–1.28), time of first prenatal care within 1–12 weeks (aOR = 5.17, 95%CI:4.19–6.37) or within 13–27 weeks (aOR = 5.56, 95%CI:4.46–6.92), previous syphilis infection (aOR = 1.64, 95%CI: 1.48–1.81), and definite syphilis infection status of sexual partner (negative: aOR = 1.73, 95%CI:1.57–1.91; positive: aOR = 1.62, 95%CI:1.34–1.95). The barriers included marital status being unmarried/divorced/widowed (aOR = 0.81, 95%CI: 0.65–0.99), pluripara (aOR = 0.58, 95%CI: 0.46–0.74), number of children ≥ 2 (aOR = 0.45, 95%CI: 0.35–0.57), and syphilis clinical stage being primary/secondary/tertiary (aOR = 0.72, 95%CI: 0.58–0.88) or unclear (aOR = 0.78, 95%CI: 0.70–0.86). Though the treatment rate of syphilis-infected pregnant women was high, the standardized treatment rate was low. The facilitators and barriers on standardized treatment of gestational syphilis were identified at the patient level.