Objective To study the clinical value of MRI in enhancing the positive rate of transrectal ultrasound prostate biopsy. Methods The medical records of 93 patients with suspected prostate cancer admitted to the hospital from May 2015 to May 2017were collected. All patients underwent transrectal ultrasound prostate biopsy in the hospital. MRI was performed before surgery to identify suspicious sites of prostate cancer. With the final pathological results as the golden standard, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of targeted ultrasound puncture and ultrasound combined with MRI targeted puncture in the diagnosis of prostate cancer were calculated. Results The 93 patients with suspected prostate cancer underwent a total of 1,116 times of systemic puncture and 132 times were positive. The positive rate of puncture was 11.8%. Ninety-three patients with suspected prostate cancer underwent a total of 86 times of targeted transrectal ultrasound prostate biopsy and 31 times were positive. The positive rate of puncture was 36.0%. A total of 124 times of transrectal ultrasound combined with MRI prostate biopsy was performed, 77 times were positive, and the positive rate of puncture was 62.1%. The positive rate of ultrasound combined with targeted MRI biopsy was significantly higher than that of simple ultrasound puncture (P<0.05). In 93 cases of suspected prostate cancer, pathology confirmed 45 cases of benign prostate hyperplasia and 48 cases of prostate cancer. The detection rate was 51.6%. The sensitivity, negative predictive value and accuracy of ultrasound combined with MRI targeted biopsy in the diagnosis of prostate cancer were 85.4%, 83.3% and 81.7%, respectively, which were significantly higher than those of ultrasound targeted puncture (52.1%, 62.3% and 67.7%) (P<0.05). Conclusion MRI can guide the biopsy, increase the positive rate of transrectal ultrasound prostate biopsy and increase the diagnostic accuracy of prostate cancer.