Objective To investigate the influencing factors of malnutrition in patients with liver cancer after radiotherapy and chemotherapy and to build a risk prediction model based on the column graph. Method A total of 155 patients with liver cancer who received radiotherapy and chemotherapy in the First Affiliated Hospital of Air Force Military Medical University Xijing Hospital from June 2019 to December 2020 and were followed up until December 2023 were selected as the study objects. According to whether there was malnutrition after radiotherapy and chemotherapy they were divided into the malnourished group n = 49 and the non - malnourished group n = 106 . Compared with baseline data the risk factors of malnutrition after chemoradiotherapy were analyzed and the prediction model was constructed with a nomogram. Result There were significant differences in age TNM stage portal vein cancer thrombus differentiation degree lymph node metastasis swallowing dysfunction gastrointestinal symptoms albumin hemoglobin and other baseline data between the malnutrition group and the non -malnutrition group P< 0. 05 . Logistic regression analysis showed that portal vein cancer thrombus low differentiation lymph node metastasis swallowing dysfunction gastrointestinal symptoms ≥2 items albumin < 40 g / L hemoglobin <110 g / L were the risk factors for malnutrition in patients with liver cancer after radiotherapy and chemotherapy P< 0. 05 . ROC curve analysis showed that the ROC curve of the line chart prediction model for predicting nutritional malnutrition in liver cancer patients after chemoradiotherapy had an area under the curve AUC is 0. 936 the sensitivity is 0. 880 and the specificity is 0. 984. Conclusion Portal vein cancer thrombolus low differentiation lymph node metastasis swallowing dysfunction digestive tract symptom items≥2 albumin <40 g / L hemoglobin <110 g / L may have an impact on malnutrition after radiotherapy and chemotherapy in patients with liver cancer. The construction of a nomogram model based on these risk factors is of certain value in predicting malnutrition so as to formulate prevention and treatment measures.