PSA is an enzyme produced by the prostate gland and is specific for prostate tissue. It is divided into serum free PSA and total PSA. it has a high predictive rate of prostate cancer and can also improve the diagnosis of limited prostate cancer and increase the chance of radical prostate cancer treatment. In conclusion, PSA is important for the diagnosis of prostate cancer, especially for the more limited and early stage prostate cancer. Early diagnosis and early treatment give patients a greater chance of survival and survival time. In addition to the dramatic changes in prostate cancer incidence and mortality over the past few decades, the clinical staging of patients with newly diagnosed prostate cancer has now substantially changed in a more favorable direction. The use of PSA has also led to a significant decrease in the pathologic staging of prostate cancer, as evidenced by the increase in the proportion of limited prostate cancer detected during radical prostatectomy. The fact that PSA screening can cause changes in clinical and pathological staging, and that there is a trend toward lower mortality in populations with universal screening, is indirect evidence that screening is beneficial.