Objective To investigate the relationship between carbohydrate antigen(CA)125 level and controlling nutritional status(CONUT)score in patients with primary liver cancer.Methods A total of 195 patients diagnosed with primary liver cancer in the First Affiliated Hospital of Nanchang University from Jan-uary 2016 to January 2020 were selected as the liver cancer group,and 195 healthy people were selected as the control group.CONUT score＜3 points were defined as normal nutrition(normal nutrition group,90 cases),CONUT score ≥3 points were defined as malnutrition(malnutrition group,105 cases).The clinical data and levels of CA125,albumin,lymphocyte count and cholesterol in each group were collected and compared.Spearman correlation analysis was used to analyze the correlation between nutritional status and CA125,and multivariate Logistic regression analysis was used to analyze the influencing factors of liver cancer combined with malnutrition.The receiver operating characteristic(ROC)curve was drawn and the area under the curve(AUC)was calculated to evaluate the ability of CA125 to distinguish malnutrition.Results The level of CA125 in the liver cancer group was higher than that in the control group(P＜0.05),while the lymphocyte count and cholesterol level were lower than those in the control group(P＜0.05).The Child-Pugh score and CA125 level of the malnutrition group were higher than those of the normal nutrition group,and the differ-ences were statistically significant(P＜0.05).Spearman correlation analysis showed that CA125 level was positively correlated with CONUT score and Child-Pugh score(r=0.657,0.647,P＜0.001),and it was nega-tively correlated with albumin,lymphocyte count and cholesterol level(r=-0.623,-0.420,-0.272,P＜0.001).There were significant differences in the COUNT score and the incidence of malnutrition among liver cancer patients with different CA125 levels(P＜0.05).Multivariate Logistic regression analysis showed that elevated CA125 level(≥35 U/mL)was a risk factor for malnutrition in hepatocellular carcinoma(OR=5.560,P=0.002).The ROC curve showed that the AUC of CA125 in the diagnosis of liver cancer combined with malnutrition was 0.826(95％CI 0.768-0.884),the cut-off value of CA125 was 25.99 U/mL,the diag-nostic sensitivity was 73.5％,and the specificity was 81.1％.Conclusion There is a certain relationship be-tween CA125 level and nutritional status in patients with primary liver cancer,and the elevated CA125 level is a risk factor for hepatocellular carcinoma complicated with malnutrition.