〔Abstract〕 Objective To investigate the value of conventional magnetic resonance imaging (MRI) combined with diffusion-weighted imaging (DWI) in preoperative TN staging diagnosis of rectal cancer. Methods A total of 85 patients with rectal cancer diagnosed by postoperative histopathology in Wugang City People's Hospital from September 2018 to September 2020 were retrospectively analyzed. All patients underwent routine MRI imaging sequence examination and DWI examination. To analyze the application value of conventional MRI sequence combined with DWI in preoperative TN staging of rectal cancer. Results According to postoperative histopathological examination, 51 cases were N0 stage, 19 cases were N1 stage and 15 cases were N2 stage in 85 patients. There were 6 cases in T1 stage, 8 cases in T2 stage, 58 cases in T3 stage, and 13 cases in T4 stage. The diagnostic sensitivity and accuracy of conventional MRI sequence combined with DWI in T staging were higher than those in N staging. Conclusion Conventional MRI imaging sequence and DWI examination complement each other, and have high application value in preoperative TN staging of rectal cancer.