Objective: Human gastric cancer SGC-7901 cells were treated with betulinic acid(BA)at the concentrations of 0, 10, 20, and 30 μg/ml, and treated with conventional chemotherapeutic drug 5-Fu as a positive control to explore its effect on cell proliferation. Trypan blue and GIEMSA staining method were used to investigate the effect of BA on cell growth inhibition and clone formation. EdU method and flow cytometry were used to explore the proliferation and cell cycle of SGC-7901 cells after treated with BA, respectively. qRT-PCR and Western blot were also applied to determine the mRNA and protein levels of cyclin D1 and cyclin B1. Results: The cell growth inhibition rate was increased after treated with different concentrations of BA in SGC-7901 cells(P＜0.05). After treated for 48 h, BA decreased the clone information and cell proliferation of SGC-7901 cells markedly in dose-and time-dependent manners (P＜0.01). Flow cytometry analysis showed that BA obviously increased the proportion of SGC-7901 cells in G1 phase but decreased the proportion of those in S phase. qRT-PCR and Western blot analysis showed that the mRNA and protein levels of cyclin D1 and cyclin B1 were significantly downregulated by BA at different concentrations(P＜0.01). Compared with the 5-Fu control group, when the concentration of BA was 20 μg/ml and 30 μg/ml, the cell proliferation ability was significantly decreased, the cell cycle was inhibited, and the expression of cyclin was reduced (all P＜0.05). Conclusion: The betulinic acid regulates the proliferation of SGC-7901 cells by inhibiting the expressions of cyclin D1 and cyclin B1, which leads to cell cycle arrest and proliferative inhibition.