Abstract: Objective To investigate the effect of Musca domestica antimicrobial peptide cecropin on cell cycle of human hepatocelluar carcinoma BEL-7402 cells and its underlying mechanism. Methods After BEL-7402 cell in vitro were treated with antimicrobial peptide cecropin of Musca domestica, the cell proliferation cycle was determined with flow cytometry analysis（FCM）with PI staining,and the expression of CHK1 and CDK2 were examined by FCM with indirect immunofluorescence technique. Results The optical microscope showed that the morphology of control BEL-7402 cells was regular, spindle-shaped adherent growth, but part of cecropin treated group cell was round, the adherent growth ability decreased and the cell number reduced. FCM showed antimicrobial peptide cecropin of Musca domestica made the cell cycle of BEL-7402 changed, decreased the ratio of G0/G1 and G2/M phase, but increased the proportion of cells in S phase, and increased the expression level of CHK1 and CDK2, compared with the control group significantly (P<0.05). Conclusion Musca domestica antibacterial peptide cecropin can effect on BEL-7402 cell cycle by adjusting the CHK1 and CDK2 expression.