【Objective】 To explore the application value of free prostate specific antigen density(fPSAD) based on rectal ultrasound in the prediction of prostate biopsy results. 【Methods】 Data of 578 patients undergoing transrectal ultrasound guided prostate biopsy during Jan.2014 and Jul.2021 were retrospectively analyzed, including prostate specific antigen(PSA) level, free prostate specific antigen(fPSA) level, fPSA/total prostate specific antigen(tPSA), prostate specific antigen density(PSAD), combined prostate specific antigen density(cPSAD), fPSAD, prostate volume and other clinical parameters. 【Results】 There were 253 cases of prostate cancer and 325 cases of prostatic hyperplasia. The positive puncture rate was 43.8%. The critical value of fPSAD was 0.05, the corresponding area under receiver operating characteristic (ROC) curve was 0.830, and the Yoeden index was 0.539. The sensitivity, specificity, diagnosis accordance rate and Kappa value of fPSAD to predict prostate cancer were 0.76, 0.77, 76.7% and 0.529, respectively. Compared with PSA, fPSA/tPSA and PSAD, PSA had the highest sensitivity (92.5%), fPSAD had the highest specificity (77.2%), and fPSAD had the highest diagnostic accordance rate (76.7%). 【Conclusion】 When transrectal prostate volume measurement is used to predict prostate cancer, fPSAD has relatively high specificity and diagnosis accordance rate, which is obviously better than using PSA, fPSA/tPSA ratio and PSAD alone in the differential diagnosis and prediction of prostate cancer and prostatic hyperplasia.