Abstract: OBJECTIVE To investigate the in vivo antitumor effect of S. pulvinata extract (SP) and its underlying mechanisms. METHODS A solid tumor H22-transplanted model in mice was established and randomly divided into normal saline control group， 5-FU chemotherapy group (30 mg/kg)， low-dose SP group (63 mg/kg)， and high-dose SP group (189 mg/kg). All mice received respective treatment once daily for 15 days. The tumor weights were monitored， and the inhibition rates as well as organ indexes were calculated. The potential mechanism was investigated using TUNEL staining， qPCR and Western blot analysis. RESULTS Compared with the control group， SP significantly inhibited tumor growth without producing obvious side-effects on body weight and immune organs. Observations from a TUNEL staining experiment demonstrated that SP noticeably induced apoptosis in tumor tissues. Moreover， qPCR showed that SP upregulated the mRNA levels of Bax and downregulated those of Bcl-2， resulting in the release of cytochrome c， which is in agreement with their protein expressions. Further Western blot analysis revealed that SP significantly activated and induced the cleavage of caspase-3， caspase-8 and caspase-9. CONCLUSION The findings clearly demonstrates that the mechanism of SP involves the induction of apoptosis. The study suggests that SP possesses potent in vivo antitumor effects against HCC.