【Abstract】Objective The purpose of this study was prospectively to evaluate the preoperative invasion of mesorectal fascia of rectal cancer with high resolution MRI and guide the multidisciplinary diagnosis and individual treatment of patients with rectal cancer.Methods From 2015 to 2019, 76 cases of rectal cancer confirmed by pathology in our hospital were collected. The routine MRI sequences included loss of shape frfse T2WI, oblique coronal frfse T2WI and oblique axial frfse T2WI. Combined with all sequences, preoperative T and N stages of rectal cancer were made to evaluate whether the mesorectum fascia was invaded, and then compared with the pathological results of TN stage.Results In 76 cases of rectal cancer, 64 cases were correctly diagnosed and 12 cases were wrong in T staging, the accuracy rate was 842%. In N staging, 52 cases were correctly diagnosed and 24 cases were wrong, the accuracy was 684%. The accuracy, specificity, sensitivity, negative predictive value and positive predictive value of MRI were 934%, 947%, 900%, 963% and 857%, respectively.Conclusion High resolution MRI enables accurately preoperative assessment MRF infiltration in rectal cancer and can carry on the local stage accurately.