Abstract: Objectives To explore the effect of mibefradil, a kind of novel calcium channel antagonists, on proliferation of human pulmonary artery smooth muscle cells (HPASMCs) induced by platelet-derived growth factor (PDGF). Methods HPASMCs were cultured in vitro, and randomly divided into control group, PDGF group, Mib group, and PDGF+Mib group.  The PDGF group was stimulated by 25 ng/ml of PDGF. Mib group was intervented by 10 μmol/L of Mib. PDGF+Mib group was treated by PDGF and Mib. The reproduction rate in 48 hours and 72 hours were detected by MMT. Cell cycle was detected by flow cytometry. The expression of proliferating cell nuclear antigen (PCNA) was observed by immunofluorescence staining (IFS). Results There were statistical differences among four groups in both 48 hours and 72 hours (P all < 0.05), especially in 72 hours. PDGF group had the highest level of HPASMC reproduction rate, and there were statistical differences as compared with the other three groups (P all < 0.05). However, the HPASMC reproduction rates were similar among PDGF+Mib group, Mib group, and control group (P all > 0.05). There were statistically differences of G0/G1 phase and S phase among four groups (P < 0.05). PDGF group had lowest G0/G1 phase cells and highest S phase cells, and there were statistically differences as compared with the other three groups (P all < 0.05). No differences were found among PDGF+Mib group, Mib group, and control group (P all < 0.05). There was obviously difference in the expression of PCNA among four groups (P < 0.05). PDGF group had the highest expression of PCNA and there were statistically differences as compared with other three groups, (P < 0.05). While the expression of PCNA was similar among PDGR+Mib group, Mib group, and control group. Conclusion Mibefradil was able to restrain remarkably the proliferation of HPASMC by inhibit the cell cycle that stimulated by PDGF, and by the expression of PCNA.