Objective To investigate the cell cycle and mechanisms of HCC Bel-7404 cell line by treatment of extract of centipede ( ECP). Method Bel-7404 cell line was cultured in vitro. ECP was applied to the interference of the growth of Bel-7404 with different drug concentration. Cell cycles and apoptosis ratios of ECP group were detected by flow cytometry (FCM). To investigate the expression of apop-tosis related genes XIAP and Bax, we also detect HCC Bel-7404 cell line after 48 hours treated with ECP by immunohistochemical method. Result The results of FCM displayed that ECP in treatment group mainly retard cell cycle phase in G0/G1 after 48 hours. The ratios of G0/ G1 .proliferation index (PI) and apoptosis ratios were significantly different between treatment group and control group when the concentrations were different. It was also significantly different between treatment group and control group when the same concentration of ECP was used. It showed that XIAP gene expression decreased gradually while Bax gene expression increased with the increase of ECP concentration, and these were statistical significance in contrast to control group ( P <0.05). Conclusion ECP mainly retarded cell cycle phase of Bel-7404 in G0/G1, suppressed the proliferation, and could induce it to apoptosis. The inhibitory effect was time - concentration dependent. The mechanisms were due to promote Bax gene and inhibit XIAP gene expression in HCC Bel-7404 cell line.