Background: To evaluate the diagnostic performance of MRI and 3D-TVS for assessment of deep myometrial invasion (MI), cervical involvement (CI), and Lymph node metastases (LNM) in endometrial cancer staging before surgery. Material/Methods: From January 2016 to December 2017, we reviewed data from 314 women with endometrial cancer who un- derwent preoperative MRI and 3D-TVS before surgery. The diagnostic sensitivity, specificity, PPV, NPV, and accuracy in detecting MI, CI, and LNM were estimated based on ultimate pathology results. Results: The sensitivity, specificity, PPV, NPV, and accuracy of MRI in the diagnosis of MI were 89.19%, 88.97%, 67.35%, 97.99%, and 89.01%, respectively, and the indexes of 3D-TVS for MI were 86.36%, 91.07%, 79.17%, 94.44%, and 89.74%, respectively. The sensitivity, specificity, PPV, NPV, and accuracy of MRI for CI were 75% and 92.35%, 40.9%, 98.13%, and 91.2%, respectively. The indicators of 3D-TVS were 77.78%, 94.29%, 63.63%, 97.06%, and 92.4%, respectively. There were no significant differences in sensitivity, specificity, NPV, and accuracy between MRI and 3D-TVS in the diagnosis of MI and CI. For MI and CI, the sensitivity of combined MRI and 3D-TVS was higher than any other single method (P<0.05). For LNM, the sensitivity, specificity, PPV, NPV, and accuracy of MRI were 58.33%, 96.26%, 63.63%, 95.37%, and 92.43%, respectively. Conclusions: 3D-TVS is equivalent to MRI in predicting MI and CI. Combined MRI and 3D-TVS can improve the assessment sensitivity, and they are useful in optimizing individualized surgical procedures. The sensitivity of MRI for LNM prediction needs to be improved.