Objective: To investigate the postoperative lymph node metastasis status and related factors of patients with early-stage low-risk endometrial cancer evaluated by the Mayo criteria in order to make the preoperative evaluation more accurate. Methods: A total of 172 patients with early-stage low-risk endometrial cancer who underwent surgery in Sichuan Provincial Cancer Hospital from 2009 to 2018 and were evaluated as early low-risk according to the "Mayo criteria" were retrospectively enrolled, and were divided into lymph node metastasis group (7 cases) and non-metastasis group (165 cases) according to the results of postoperative pathological examination. The postoperative pathological examination results and prognosis of all patients were collected. The lymph node metastasis of the two groups was analyzed. The multiple logistic regression model was used to analyze the related factors of lymph node metastasis, and the area under the curve (AUC) of the relevant factors was calculated by using the receiver operating characteristic curve to predict the postoperative lymph node metastasis of patients. Results: The age of 172 patients was (53.0±8.6) years, and the follow-up [M(Q1,Q3)] was 64.1 (46.2, 91.4) months, among whom 2 relapsed and 1 died. Among the 7 patients with lymph node metastasis, 5 cases had pelvic lymph node metastasis, 1 case had pelvic lymph union and abdominal para-aortic lymph node metastasis, 1 case had isolated abdominal para-aortic lymph node metastasis, 3 cases had two lymph node metastases, and 4 cases had intrailiac lymph nodes being the most common metastasis site. Multivariate analysis showed that preoperative serum cancer antigen (CA) 125 was the relevant factor for postoperative lymph node metastasis, with an OR value (95%CI) of 1.022 (1.001-1.043) (P=0.042), with AUC (95%CI) of CA125 predicting lymph node metastasis of 0.850 (0.761-0.939) (P=0.002), and the optimal cut-off value of CA125 was 29.305 U/ml with the sensitivity of 85.7% and the specificity of 80.6%. Conclusions: When CA125>29.305 U/ml, patients with early-stage low-risk endometrial cancer assessed by the Mayo criteria, had an increased risk of lymph node metastasis. Therefore, adding preoperative serum CA125 level as an evaluation index on the basis of the classic "Mayo criteria" may help conduct more accurate preoperative evaluation and better identify early-stage low-risk EC patients.