[Background] Excessive gestational weight gain among women has increased dramatically worldwide, which is associated with maternal and infants’ health. Recent evidence supports that gut microbiota may be an important regulation factor correlated with numerous human diseases. [Objective] To explore maternal gut microbiota diversity and composition at late pregnancy and changes of maternal gut microbiota with different gestational weight gain status, evaluating the effect of gestational weight gain on maternal gut microbiota. [Methods] we collected 62 pregnant women’s fecal samples at late pregnancy (36.82±2.19 gestation weeks), using high-throughput Miseq sequencing technology for sequencing 16S rRNA gene sequence in the V3?V4 region of samples. [Results] maternal gut microbiota of excessive gestational weight gain has a significantly lower diversity. The most important five genus of gestational weight gain are Alistipes spp., Eubacterium-nodatum group spp., Oxalobacter spp., Raoultella spp. and Odoribacter spp. And the intensity of correlation of Alistipes spp. is the most strong and abundant. There are no differences between adequate and excessive groups in gut microbiota structure. [Conclusion] Gestational weight gain can affect maternal gut microbiota at late pregnancy and the balance of gut microbiota will stimulate a healthy development of maternal and infants.