Aim To investigate the effect of JNK in the proliferation and β-catenin nuclear accumulation stimulated by platelet derived growth factor-BB(PDGF-BB). Methods The inhibitory effect of JNK inhibitor-SP600125(10,20,40 μg/L) in the PDGF-BB stimulating vascular smooth muscle cell proliferation was detected by CCK8 assay.Expression of JNK,p-JNK,nuclear and cytosolic β-catenin stimulated by PDGF-BB at different time point was examined.The effect of SP600125 on the nuclear accumulation of β-catenin was detected by Western Blotting and immunofluorescence. Results CCK8 OD value was greatly enhanced after stimulated by PDGF-BB(50 μg/L)(0.876±0.041 vs 0.370±0.082,P><0.01),it was significantly inhibited by JNK inhibitor-SP600125(10,20,40 μg/L)(0.635±0.063,0.470±0.044,0.381±0.054 vs 0.876±0.041,P><0.01) in a concentration-dependent manner.After stimulated by PDGF-BB,expression of p-JNK and nuclear β-catenin increased over time,and p-JNK at 15 minute and nuclear β-catenin at 60 minute reached its peak.The expression of p-JNK at 15 minute and nuclear β-catenin at 60 minute was inhibited by using SP600125(10,20,40 μg/L)in a concentration-dependent manner.The immunofluorescence test also showed that nuclear accumulation of β-catenin in vascular smooth muscle cell was significantly inhibited by SP600125. Conclusion The phosphorylation of JNK was a key step in the nuclear accumulation of β-catenin induced by PDGF-BB.