Here, we showed that ERRα, which exhibited an up-regulation pattern in metastatic CRPC and also xenograft model of CRPC, could function to promote the resistance to androgen-deprivation in prostate cancer cells and also enhance the intratumoral androgen biosynthesis via its transcriptional regulation of some key androgen biosynthetic enzyme genes, including CYP11A1 and AKR1C3. The gene discussed is CYP11A1; the disease is prostate cancer.