Background and Aims The current main approach for assessing the prognosis of medullary thyroid carcinoma (MTC) is the TNM staging system, but it cannot provide individualized prognosis prediction for patients. Therefore, there is a need to develop a precise prognostic indicator system specifically for MTC. This study was conducted to analyze the factors influencing postoperative survival in MTC patients and construct a postoperative survival nomogram for MTC.Methods MTC data from the SEER database from 2004 to 2015 were selected, and a total of 1 884 eligible patients were included in the study. The patients were randomly divided into a training set (1 413 cases) and a validation set (471 cases) at a ratio of 3∶1. The baseline clinical data and characteristics were compared between the two groups. Univariate and multivariate Cox regression models were used to identify independent factors for MTC survival, and Kaplan-Meier survival curves were used to analyze their impact on prognosis. A survival nomogram for postoperative MTC patients was established based on the results of Cox regression analysis. The nomogram was validated and evaluated using concordance index, ROC curve, area under the curve (AUC), calibration curve, and decision curve analysis (DCA).Results The results of univariate analysis showed that sex, age, primary tumor stage, lymph node metastasis, distant metastasis, total thyroidectomy, extrathyroidal. invasion, and radiotherapy were all associated with patients' prognosis (all P<0.05). The results of Cox regression analysis showed that sex, age, distant metastasis, extrathyroidal. invasion, total thyroidectomy, and radiotherapy were independent prognostic factors for MTC patients (all P<0.05). Kaplan-Meier survival curves demonstrated that male patients, age ≥49 years, presence of distant metastasis, extrathyroidal invasion, absence of total thyroidectomy, and receipt of radiotherapy had worse prognosis. Nomograms for 2-, 5-, and 10-year survival of MTC patients were constructed using variables that included sex, age, distant metastasis, and extrathyroidal invasion and surgical procedure. The concordance index for the training set of the nomogram was 0.755 (95% CI=0.741-0.769), and for the validation set, it was 0.725 (95% CI=0.699-0.769). The ROC curve was used to evaluate the discriminatory ability of the nomogram, with AUC values of 0.79, 0.779, and 0.766 for the training set at 2-, 5-, and 10-years, respectively, and 0.78, 0.725, and 0.733 for the validation set. The calibration curve showed good consistency between the predicted survival rates and actual survival rates. DCA demonstrated that the nomogram had greater net benefit compared to the AJCC 6th edition TNM staging system in 5- and 10-year survival assessment.Conclusion Sex, age, distant metastasis, extrathyroidal. invasion, and surgical approach are independent factors influencing the survival of MTC patients. The postoperative survival nomogram model for MTC can provide more accurate individual survival prediction to assist clinicians in making appropriate personalized clinical decisions.