Objective To study the accurate rates of MRI and CT in the diagnosis of patients with prostate cancer of different pathological staging. Methods 61 patients with confirmed prostate cancer in our hospital were selected as the research objects. All of them underwent CT plain scan/enhanced scan (dual phase dynamic scan) and MRI scan. The accurate rates of the two detection methods for the detection of A/B and C/D stage of prostate cancer were compared. Results Among 61 patients in this study, 3 cases were of A stage, B stage 16 cases, C stage 18 cases and D stage 24 cases. The detection rate of CT plain scan/enhanced scan for A/B was 47.37%. There were 10 cases missed diagnosis or misdiagnosed, 6 cases misdiagnosed as benign prostatic hyperplasia and 4 cases missed diagnosis. The detection rate of MRI for A/B was 89.47% and 2 cases were missed diagnosed. The detection rate of MRI was significantly higher than that of CT (P < 0.05). The detection rate of CT plain scan/enhanced scan for C/D was 92.86%. 3 cases were misdiagnosed, including 2 cases of benign prostatic hyperplasia and 1 case of bladder cancer; The detection rate of MRI for C/D was 95.24% and 2 cases misdiagnosed were benign prostatic hyperplasia. The detectiin rate of MRI was slightly higher than that of CT (P>0.05). Conclusion The accuracy of MRI in diagnosis of A and B stage of prostate cancer is significantly higher than that of CT plain scan and enhanced scan. The main causes are that only the volume of prostate in stages A and B of prostate cancer increases, there is no significant change of density and the obscure boundaries have impact in CT diagnosis. The two detection methods can accurately detect C and D stage prostate cancer. Considering cancer tissues having worn out the envelopes, the morphological changes of the prostate was significantly related. However, MRI can judge whether the envelopes are invaded by cancer cells or not, so compared with CT, its diagnostic value is higher.