Prostate cancer test psa is checked by drawing blood. PSA is also known as prostate-specific antigen, which exists in the epithelial cells of prostate ducts. When prostate cancer occurs, PSA can be found to be elevated in the serum through blood sampling, and PSA can be divided into t-PSA (total serum PSA), c-PSA (compound PSA), and f-PSA (free PSA) in the serum, and the normal value of t-PSA is <4 μg/L, the normal value of f-PSA is <0.8 μg/L, the ratio of f-PSA/t-PSA is 0.25. The normal value of t-PSA is <4 μg/L, f-PSA is <0.8 μg/L, and the ratio of f-PSA/t-PSA is 0.25. If prostate cancer occurs, 60%~90% of patients' blood t-PSA level can be significantly increased, and the serum t-PSA level can be significantly decreased after surgical resection. It is recommended to consult the doctor in time when PSA is elevated, and to identify the cause of the disease and then carry out treatment.