Objective: To explore and analysis the diagnostic value of serum CEA, CA19-9 combined with CRP in digestive tract malignant tumors. Methods: From August 2019 to May 2022, 150 cases of patients with gastrointestinal malignant tumors diagnosed and treated in our hospital were selected as the gastrointestinal malignant tumor group, and 150 cases of healthy people who received physical examination in our hospital during the same period were selected as the healthy group. The serum carcinoembryonic antigen（CEA）,carbohydrate antigen 19-9（CA19-9）, and C-reactive protein（CRP） contents of the two groups of cases were collected, and the patients’ pathological features were investigated and determined the diagnostic values. Results: The levels of serum CEA, CA19-9 and CRP in digestive tract malignant tumor group were higher than those in healthy group（P<0.05）. The positive rates of CEA, CA19-9 and CRP in the digestive tract malignant tumor group were 54.7 %, 58.7 % and 60.7 %, which were higher than those in the healthy group（3.3 %, 4.0 %and 4.7 %）（P<0.05）. In the digestive tract malignant tumor group, there were significant differences in serum CEA, CA19-9 and CRP levels in patients with different histological differentiation, clinical stages and lymph node metastasis（P<0.05）. The serum CEA, CA19-9combined with CRP were diagnosed as positive in 113 cases, and 3 cases were diagnosed as positive in the healthy group. The diagnostic sensitivity and specificity of serum CEA, CA19-9 combined with CRP in digestive tract malignant tumors were 75.3 %（113/150） and 98.0 %（147/150）, respectively. Conclusion: Patients with malignant tumors of the digestive tract are often accompanied by high expression of serum CEA, CA19-9 and CRP, and the pathological characteristics are correlated with the contents of serum CEA, CA19-9 and CRP. The sensitivity and specificity of serum CEA, CA19-9 combined with CRP in the diagnosis of digestive tract malignant tumors are relatively good. [ABSTRACT FROM AUTHOR]