Abstract: Objective To study the effect of siRNA to MDM2 on cell proliferation and MDM2 expression in prostate the cancer cell PC3. Methods PGCsilencer^TM-MDM2 siRNA was constructed and transfected into the PC3 cells. MDM2 gene expression was detected by RT-PCR and protein expression was analyzed using western blot. The inhibitory effect on cell proliferation was determined by MTT assay. The cell apoptosis was observed by flow cytometer. Results The results of RT-PCR and western blot showed that the expression of MDM2 was inhibited in the siRNA transfected group and the highest inhibitory rate was 65%. The results of MTT and flow cytometer showed that siRNA could suppress the proliferation and induce apoptosis of PC3 cells. Conclusion siRNA of MDM2 could significantly inhibit MDM2 expression, the proliferation of PC3 cells and induce apoptosis of PC3 cells.