Abstract: Objective: To explore the application value of combined detection of serum tumor markers carbohydrate antigen 125 (CA125),carbohydrate antigen 199 (CA199),carbohydrate antigen 72-4 (CA72-4),and carcinoembryonic antigen (CEA) in gastrointestinal tumors. Methods: Clinical data of 158 patients with gastrointestinal tumors (observation group) and 46 patients with benign gastrointestinal lesions (control group) were randomly selected for retrospective analysis.CA125,CA199,CA72-4,and CEA were detected in the two groups and statistically analyzed to evaluate the application value of CA125,CA199,CA72-4,and CEA in patients with gastrointestinal tumors. Results: The levels of CA125,CA199,CA72-4,and CEA in the observation group were significantly higher than those in the control group (P<0.01).The levels of CA125,CA199,CA72-4,and CEA in gastrointestinal tumors of different pathological differentiation types were as follows:well differentiated adenocarcinomaP<0.05 to P<0.01).The levels of CA125,CA199,CA72-4,and CEA in gastrointestinal tumors with lymph node metastasis were higher than those without lymph node metastasis (P<0.05 to P<0.01).The AUC of the ROC curve for the combined detection of CA125,CA199,CA72-4,and CEA in the diagnosis of gastrointestinal tumors was higher than that of the individual detection of the above four indicators,and the difference was statistically significant (P<0.01). Conclusions: The combined detection of CA125,CA199,CA72-4,and CEA in patients with gastrointestinal tumors can provide a basis for clinical diagnosis of gastrointestinal tumors,and can also accurately analyze their condition,which is beneficial for understanding the pathological differentiation and lymph node metastasis of tumors.