Objective To investigate the predictive value of modified nutrition risk in the critically ill（mNUTRIC）score in patients after cardiopulmonary bypass. Methods Clinical data of 252 patients after cardiopulmonary bypass surgery were collected from June 2020 to August 2022 in the intensive care unit（ICU）of Maoming Hospital Affiliated to Southern Medical University. Patients were divided into high and low nutritional risk groups based on modified NUTRIC score within 24 hours of ICU admission. Binary logistic regression analysis was used to evaluate the risk factors affecting the prognosis of patients. The receiver operating characteristic（ROC） curve was used to evaluate the performance of modified NUTRIC score on hospital mortality in patients after cardiopulmonary bypass surgery. Results The rate of renal replacement therapy，duration of mechanical ventila⁃ tion，length of ICU stay and hospital mortality in the high nutritional risk group were higher than those in the low nutritional risk group（P < 0.05）. Multivariate analysis showed that mNUTRIC score was an independent risk factor for the prognosis of patients after cardiopulmonary bypass（P < 0.05）. The area under the curve predicted by the mNUTRIC score was 0.824，with a sensitivity and specificity of 65.0% and 89.6%，respectively. Conclusions mNUTRIC score is a good predictor of hospital mortality in patients after cardiopulmonary bypass surgery and is expected to be used in clinical application as an evaluation index after cardiac surgery.