Objective：To investigate the effects of ripasudil on proliferation and migration of human pulmonary arterial smooth cells（HPASMCs）induced by platelet-derived growth factor（PDGF）-BB and the mechanisms underlying. Methods：Cultured HPASMCs were divided into four groups：the control group，the PDGF-BB-treated group，the PDGF-BB and ripasudil-treated group and the ripasudil-treated group. CCK-8 was applied to investigate cell viability and EdU assay was used to evaluate the proliferation of HPASMCs. Transwell assay was employed to examine cell migration. The expression of matrix metalloproteinase-2（MMP-2）was determined by real-time PCR and Western blot. The levels of phosphorylated myosin phosphatase target subunit 1（MYPT1），extracellar regulated protein kinases 1/2（ERK1/2），p38，and protein kinase B（PKB/Akt）were detected by Western blot. Results：Compared with the control group，ripasudil blocked the proliferation and migration of HPASMCs challenged by PDGF-BB（P＜0.01）. Ripasudil suppressed PDGF-BB-induced upregulation of MMP-2（P＜0.05）. Moreover，ripasudil inhibited PDGF-BB-induced phosphorylation of MYPT1，ERK1/2，p38，and Akt（P＜0.05）. Conclusion：Ripasudil significantly inhibited PDGF-BB-induced proliferation and migration of HPASMCs，which might be attributed to the inhibition of MYPT1，ERK1/2，p38 and Akt. Ripasudil，a Rho kinase inhibitor，might be a potential therapeutic option in PAH.