Abstract： Objective To investigate the effects of microRNA?224 (miRNA?224) on the proliferation,apoptosis,invasion and migration of prostate cancer. Methods The recombinant lentiviral vectors with overexpressed miR?224 were established to transfect prostate cancer cell lines PC3 and LNCaP (overexpressed miR?224 group),and empty vectors to transfect PC3 and LNCaP (empty vector control group). Real?time fluorescence quantitative PCR was used to determine the expression of miR?224 in each group. Using cell proliferation assay ,scratch assay ,cell invasion assay and flow cytometry to determine cell proliferation,migration,invasion and apoptosis in each group. The subcutaneous tumor xenograft models in nude mice were established ,and the effects of miR?224 on tumor growth were determined. Results Compared with the empty vector control group,the miR?224 expression was significantly increased (both P<0.01)and the cell proliferation was significantly decreased(all P<0.05)in the overexpressed miR?224 group. Scratch assay showed that miR?224 significantly inhibited prostate cancer cell migration(both P<0.01). Flow cytometry showed that overexpressed miR?224 promoted prostate cancer cell apoptosis(both P<0.01). Cell invasion assay showed that the increased expression of miR?224 decreased the invasion of tumor cells (both P<0.05). The xenograft tumor of prostate cancer cell in nude mice showed that the increased expression of miR?224 inhibited the growth of xenograft tumor. Conclusion MiR?224 plays a role of tumor inhibition in prostate cancer.