Objective To explore the inhibitory effect of down-regulating Bloom helicase gene using RNA interference (RNAi) vectors on prostate cancer PC3 cells. Methods The BLM-RNAi vectors constructed previously in our lab were transfected into prostate cancer PC3 cells, and the proliferation ability of PC3 cells was detected with MTT at 24 h, 48 h and 72 h after transfection of recombinant vectors. At 48 h, the invasion and migration ability was detected with Transwell chamber assay, migration distance was examined with cell scratch test, and cell apoptosis was detected with Hoechst/PI. Results The proliferation ability of cells after transfection was significantly weaker than that in the blank control group (P<0.05), the number of cells across Transwell membrane after transfection was significantly less than that in the blank control group (invasion ability: 119±24, 118±30 vs 227±38, P<0.05; migration ability: 122±13, 121±47 vs 277±32, P<0.05), cell scratch test also showed that the wound healig rate and cell migration distance in the experimental group were significantly lower than those in the blank control group (P<0.05), and cell apoptosis in the experimental group was more notable compared with the blank control group. Conclusion RNAi vectors targeting Bloom helicase gene can inhibit the proliferation, migration and invasion ability of prostate cancer PC3 cells, and increase the cell apoptosis, which may cast new lights on the gene therapy of prostate cancer.