Objective To investigate the value of high-resolution 3.0T MR in the assessment of local infiltration of preoperative rectal cancer.Methods A total of 168 patients pathologically proved rectal cancer underwent both conventional pelvic and rectal high-resolution before operation, and the imaging findings were reviewed retrospectively.The accuracy of preoperative high-resolution 3.0T MR in prediction of pathological staging was assessed,and the characteristic imaging features of local infiltration in preoperative rectal cancer were discussed.Results The relationship between circumference invasion of colorectal cancer and the pathological T staging was moderately positive (rs=0.530,P=0.003).Compared the staging of colorectal cancer on MRI with pathologic T staging,the overall diagnostic accuracy was 84.52%,and there was a stronger correlation between MRI findings and pathological staging (rs=0.837,P=0.001).The best single parameters for diagnosing T3 stage rectal cancer on MRI were nodular convex of the tumor and muscular signal interruption,with 91.1% specificity and 89.7% sensitively respectively.And the best combination of parameters was the cord appearence of intestinal wall and muscular signal interruption,with 89.3% specificity and 78.0% sensitively respectively.Conclusion High-resolution 3.0T MR can be preferable to evaluating local infiltration of rectal cancer, showing a higher clinical value to asseee T staging of preoperative rectal cancer.