Objective: To explore the high risk factors of atypical endometrial hyperplasia (AEH) postoperative pathological upgraded to endometrial carcinoma (EC). Methods: We retrospectively analyzed the clinical data of 168 patients with AEH, evaluated the diagnostic value of diagnostic curettage, hysteroscopy biopsy and intraoperative frozen pathology according to the standard of postoperative paraffin pathology. According to the characteristics of the clinical cases, the risk of postoperative upgrading to cancer was evaluated and leakage of EC was avoided. Results: The diagnostic coincidence rate of hysteroscopy biopsy (72.72%) is higher than that of diagnostic curettage (66.67%), the difference was not statistically significant (P>0.05). The intraoperative frozen pathology have higher diagnostic coincidence rate for AEH and EC, and the higher the preoperative pathology score, the higher the risk of upgrade to EC. Among the 54 patients with EC, 38 cases (70.37%) are with high differentiation cancer and 46 cases (85.19%) with Ia patients. Age, postmenopausal status, obesity, preoperative ultrasound and intraoperative section of the uterine cavity were the sensitive indexes for predicting EC. Conclusion: AEH has a tendency to become EC, especially the preoperative pathological score is high, and the patients who are menopausal, obese, preoperative ultrasound indicate abundant blood flow, and the endometrium is not smooth in the operation. Most of the cancers are well differentiated, mainly in the early stage. The intraoperative frozen pathology can improve the accuracy of diagnosis, however, the possibility of missed diagnosis cannot be ruled out.