Abstract: Prostate cancer is the most common malignant tumor in the male urinary system. miRNA is a newly discovered small non-coding RNA of 19-23bp nucleotides, which was involved in regulating many important biological functions, even play a key role in tumor development. The blood research has indicated miRNA in blood could be a biomarker for diagnosis of prostate cancer but did not find specific extracellular miRNA as a prostate cancer biomarkers. Investigate the expression and the action mechanism of miRNA of prostate cancer have a great meaning to further discuss the pathogenesis of prostate cancer, search for new diagnostic and therapeutic method. This review focuses on the different abundance of miRNA among healthy population, patients with prostate cancer, patients with metastatic prostate cancer and moderating effect of miRNA of prostate cancer on tumor radiosensitivity, try to explore the clues of miRNA as biological markers for prostate cancer.