Abstract: Objective To evaluate the diagnostic capabilities of conventional MRI (T1WI, T2WI and Gd-enhancement T1WI) for differentiating prostate cancer from benign prostatic disorders in prostatic peripheral zone (PZ). Methods Respectively analyze the characteristics of conventional MRI in 46 cases of prostate cancer and 25 cases of benign prostatic disorders (with 28 lesions). Six indexes were initially screened by χ²-test, and receiver operating characteristic curves (ROC) of these indexes were depicted, then Bayes discriminator was applied to discriminate all the lesions according to the indexes with statistic meaning. The discriminant function was evaluated with new sample validation. Results The indexes showing statistics meaning between prostate cancer and benign prostatic disorders were uniform low SI on T2WI, shape, pseudocapsule extension, prostate-capsule extension, size change of PZ with lesion and enhancement style. Furthermore, uniform low SI on T2WI, enhancement style and size change of PZ with lesion were consist of the function after discrimination, AUC of these 3 indexes were all above 0.7, which were wider than that of the other 3 indexes. The discriminating accuracy rates of the new sample for benign prostatic disorders and prostate cancer were 83% and 77%. Conclusion The importance of uniform low SI on T2WI, enhancement style and size change of PZ with lesion should be highlighted in the differentiation of prostate cancer and benign prostatic disorders in PZ.