Background: Previous studies showed the significant diversity of the genomic landscapes between castration sensitive prostate cancer (CSPC) and castration resistant prostate cancer (CRPC). AR, TP53/RB1, and BRCA2/ATM have been reported to contribute to the development of CRPC. In addition, CDK12 has recently reported to lead to the worse response to AR-targeted therapies. We are aimed to clarify the landscape of somatic gene alterations in CSPC and CRPC by multiple-gene targeted sequencing and discover the differential genes between the two treatment stages in order to guide clinical treatment. Methods: We recruited 413 prostate cancer patients including 230 CSPC and 183 CRPC. Cell-free DNA was extracted from plasma samples. Targeted sequencing of 50 genes was performed, which involved in DNA damage repair (DDR) pathway, AR pathway, TP53/RB1, etc. Chi square test or Fisher test were used to analyze the differences between two cohorts. Results: A total of 33.04% (76/230) CSPC patients carried somatic gene alterations, including 16.96% (39/230) in DDR pathway, 19.57% (45/230) in AR pathway and 7.39% (17/230) in TP53/RB1. The most frequent altered gene in CSPC was FOXA1 (9.13%,21/230), followed by NCOR2 (6.52%,15/230) and TP53 (5.65%,13/230). For CRPC patients, 66.67% (122/183) carried somatic gene alterations, including 44.81% (82/230) in DDR pathway, 49.73% (91/230) in AR pathway and 25.68% (47/183) in TP53/RB1. The most frequent mutated gene in CRPC was AR (33.33%,61/183), followed by FOXA1 (23.50%,43/183) and CDK12 (17.49%,32/183). Mutation frequencies of certain genes in CRPC patients were significantly higher than CSPC patients, including CDK12 (p < 0.001), BRCA2 (p = 0.006), ATM (p = 0.003), ATR (p = 0.007), AR (p < 0.001), FOXA1 (p = 0.001), SPOP (p = 0.002), ZBTB16 (p = 0.02), TP53 (p = 0.001), RB1 (p = 0.04) and PTEN (p = 0.001). Conclusions: It was the first study which explored the genomic alterations in Chinese CSPC and CRPC patients by liquid biopsy. These findings confirmed the genomic diversity between CSPC patients and CRPC patients, which could guide the individualized and precise management of prostate cancer in general practice. Furthermore, our findings indicated that somatic alterations in AR, CDK12, BRCA2, ATM and TP53/RB1 might contribute to the development of CRPC.