OBJECTIVE To compare the accuracy of different methods of measuring the prostate volume (PV) based on the manifestations of prostatic ultrasonography and MRI. METHODS Using the drainage method, we measured the volumes of 101 prostatic specimens collected from radical prostatectomy. And with the measures obtained as reference standards, we calculated the PV of the patients with the maximum width (W), height (H) and length (L) of the prostates obtained preoperatively by transabdominal ultrasonography (TAUS), transrectal ultrasonography (TRUS) and MRI using the ellipsoidal formula (PV = W × H × L × 0.52), bullet formula (PV = W × H × L × 0.65) and 3D reconstruction technology. We evaluated the accuracy of the above methods using the Mann-Whitney U test, intraclass correlation coefficient (ICC), and Bland-Altman scatterplot. RESULTS No statistically significant differences were observed between the specimen and preoperative PVs. The ICCs of the specimen PVs obtained by MRI 3D reconstruction, TRUS bullet formula, MRI ellipsoidal formula and TAUS ellipsoidal formula were 0.978, 0.862, 0.857 and 0.745, respectively. The Bland-Altman scatterplot exhibited that the preoperative PV calculated by MRI 3D reconstruction had the highest consistency with that of the specimen PV, followed by that measured by TRUS bullet formula and that obtained by MRI ellipsoidal formula, while that determined by TAUS ellipsoidal formula had a low consistency. CONCLUSIONS The MRI 3D reconstruction technology is the most reliable method for the measurement of PV, followed by TRUS bullet formula, but the latter is recommended for its high applicability in clinical practice.