Objective To evaluate the value of 1.0T MRI and 64 slice MSCT in preoperative T staging of middle and low rectal cancer. Methods The clinical data of 93 patients with pathologically confirmed middle and low rectal cancer were collected. They were divided into MRI group and MSCT group according to the preoperative diagnostic method.Results of preoperative diagnosis and T staging were compared between the two groups, and the results were compared with postoperative pathological results. The diagnostic value of the two methods was evaluated. Results The total accuracy of MSCT for different stages was significantly lower than that of MRI [65.1% (28/43) vs 88.0% (44/50)] (P<0.05). The sensitivity, accuracy and Kappa value of MSCT diagnosis for T1-2 were 64.3%, 86.0% and 0.629, respectively. The diagnostic efficiencies of T3 were 62.5%, 86.0% and 0.539, respectively, while the diagnostic efficiencies of T4 were 66.7%, 88.4% and 0.634, respectively. The diagnostic efficiencies of 1.0T MRI for T1-2 were 80.0%, 86.0% and 0.706, respectively. The diagnostic efficiencies of T3 were 86.2%, 90.0% and 0.799, respectively, while the diagnostic efficiencies of T4 were 75.0%, 96.0% and 0.728, respectively. Conclusion Both of 1.0T MRI and 64 slice MSCT can be used for preoperative T staging of middle and low rectal cancer. Their diagnostic value is similar, but the diagnostic efficiency of MRI is slightly higher than that of MSCT, especially in differential diagnosis of tumors at stage T2 and T3.