Abstract: Objective To study the value of serum free prostate specific antigen (F-PSA), total prostate specific antigen (T-PSA) and (F-PSA)/(T-PSA) ratio in the diagnosis of prostatic disease. Methods 190 patients of prostatic diseases from urology surgery in our hospital from Oct 2012 to Oct 2014 were selected in the study. F-PSA and T-PSA were determined by CMIA in 190 patients and 100 controls, and the ratio of F-PSA to T-PSA was calculated. Results Serum F-PSA, PSA in benign prostatic hyperplasia (BPH) group and prostate cancer (PCa) group were significantly higher than that in normal group (P<0.01), while had significant difference between BPH group and PCa group (P<0.01). When it was between 4-10ng/ml, T-PSA in BPH had no significant difference with that in PCa group (P>0.05). The ratio of F-PSA to T-PSA in PCa group was significantly lower than that in BPH group (P<0.01). Conclusion The value of combined detection of F-PSA, T-PSA and F-PSA/T-PSA could be significantly better than determining PSA alone in the diagnosis of prostatic disease.