Abstract: Objective To investigate the effect of Tetrandrine(TET) on the proliferation and apoptosis of prostate cancer cells PC3 and the possible mechanism. Methods PC3 cells were treated with different concentration of TET(0, 1, 2, 4, 6, 8, 10μg/ml). Trypan blue exclusion assay and MTT assay were used to detect the inhibition effect of TET on the proliferation of PC3. Cell apoptosis was analyzed by flow cytometry. Expression of caspase3 and PARP protein were detected by Western blot. Results The inhibition rate of PC3 cells after treated with 2 μg/ml TET for 24h was (20.96±1.72) %, and the inhibition effect was increased with the increase of TET concentration. The inhibition rate accounted for (89.23±4.12)% when treated with 10μg/ml TET for 24h. TET could also induce the apoptosis of PC3. There was obvious cleavage activation of Caspase-3 and deactivation of PARP after treated with TET. Conclusion TET could inhibit the growth of PC3 cells by inducing typical apoptosis. The mechanism may be related to the cleavage activation of Caspase-3 and deactivation of PARP.