Objective To analyze the efficacy of transrectal ultrasound (TRUS) combined with shear wave elastography (SWE) in the diagnosis and TNM staging of rectal cancer.Methods The clinical data of 86 patients with rectal tumor admitted to our hospital from December 2019 to February 2021 were retrospectively analyzed. All patients underwent TRUS and SWE before operation. The sensitivity, specificity and accuracy of TRUS, SWE and their combination in the diagnosis and staging of rectal cancer were recorded. E_max and E_mean values of tumor foci, surrounding fat tissues, and normal rectal wall were compared between patients with rectal cancer and rectal adenoma. The receiver operating characteristic (ROC) curves were applied to analyze the values of TRUS, SWE and their combination in the diagnosis of rectal cancer.Results The diagnostic sensitivity of TRUS combined with SWE was 97.18% (95% CI: 79.7%, 98.9%), with the specificity of 86.67% (95% CI: 71.0%, 97.8%) and the accuracy of 95.35% (95% CI: 78.2%, 98.5%). The area under the ROC curve (AUC) of TRUS combined with SWE for diagnosing rectal cancer was 0.968 (95% CI: 0.894, 1.000). The sensitivity of TRUS combined with SWE for diagnosing stage T1, T2, T3 and T4 rectal cancer was 94.12% (95% CI: 75.5%, 94.0%), 90.91% (95% CI: 71.8%, 91.8%), 100.00% (95% CI: 99.2%, 100.00%), 100.00% (95% CI: 99.0%, 100.0%), respectively. The E_max and E_mean values in the rectal cancer group were higher than those in non-rectal cancer group (P < 0.05). Besides, E_max and E_mean values were significantly different among the stages (P < 0.05), and the more advanced the T stage, the higher the E_max and E_mean values.Conclusions TRUS combined with SWE is more accurate in diagnosing and staging rectal cancer, which can provide certain reference basis for clinical identification of the lesions and determination of their pathological degrees.