Objective To detect the change of proliferation and further find out the survival state of vascular smooth muscle cells（ VSMCs） after knockdowned the expression of Notch 3 by RNA interference in different surroundings. Methods Ox-LDL and IGF-1 were applied to intervene normal VSMCs and Notch knockdowned VSMCs. Cell growth was observed under inverted microscope. Cell growth curve was detected by CCK-8. Results The growth curve of the ox-LDL control group was obviously higher than that of the ox-LDL positive group. During the first four days， the growth curve of ox-LDL control group， IGF-1 positive group and IGF-1 control group were higher than that of the other groups. This trend was more obvious in the fifth and sixth day. The proliferative rate was similar among the 3 groups. Conclusions For Notch 3 signal system， ox-LDL and IGF had different effects. When Notch 3 was inhibited， the proliferation of ox-LDL decreased. However， the proliferation promoting effect of IGF-1 on VSMCs remained.