Objective To investigate the effects of insulin-like growth factor-1 (IGF-1) and oxidized low density lipoprotein (oxLDL) on expression of phosphatase PHLPP1 in vascular smooth muscle cells (VSMCs). Methods Rabbit aortic VSMCs were cultured. VSMCs proliferation ability was determined by measuring cell number and mitochondrial dehydrogenase (MD) activity with MTT assay. Western blot was used to detect the protein expression of phosphatase PHLPP1. Results IGF-1 (100μg/L) increased cell number and MD activity to 3.02 and 3.59 times of that in control group. oxLDL(50μg/ ml) elevated the above two parameters to 2.03 and 2.91 times respectively. Western blot showed that IGF-1 and oxLDL inhibited the expression of PHLPP1 to 39.27% and 40.26% of the control group (P<0.01). Conclusion IGF-1 and oxLDL may enhance the proliferation of VSMCs by decreasing the expression of phosphatase PHLPP1.