Abstract: In order to investigate the pro-apoptotic effects of Forsythia suspensa extract FS-4 on gastric cancer cells SGC-7901 in vitro, in the experiment, the inhibition of FS-4 on the proliferation of gastric cancer cells was observed by MTT colorimetric method; the morphological changes of apoptosis were observed by AO/EB dual fluorescence staining and transmission electron microscopy, and the apoptosis rate of the cells was measured by flow cytometry. The results showed that the inhibitory effect of FS-4 on the proliferation of gastric cancer cells SGC-7901 was dose-and time-dependent, and its 36-h half-inhibitory concentration(IC₅₀) was only 3.23 μg/mL. The cells showed typical apoptotic cell morphology after FS-4 treatment, and the apoptotic effect of FS-4 on cells showed a significant concentration-dependence. These results indicated that FS-4 could inhibit the proliferation of gastric cancer cells SGC-7901 and induce apoptosis.