Abstract：Objective To investigate clinical significance of the serum tumor markers (CEA, CA19-9, CA242, CA50, CA72-4) detection combined with multi-slice spiral CT examination in the diagnosis of colorectal cancer. Methods A retrospective study of the changes of tumor markers levels and CT image in 80 cases of healthy people, 78 cases of intestinal benign disease patients (30 cases of colitis, 48 cases of colon, rectum polyp), 96 cases of colorectal cancer (50 cases of colon cancer, 46 cases of rectal cancer) were carried out and SPSS17.0 software was used for statistical analysis. Results The serum tumor markers in patients with colorectal cancer were significantly higher than those in healthy control group and benign colorectal lesion. The positive rate of combined tumor markers detection in diagnosis of colorectal cancer was 93.75% and the specificity was 91.25%, it was better than single tumor marker detection. The positive rate of multi slice spiral CT in colorectal cancer diagnosis was 91.67% and the specificity was 98.75%. The positive rate of colorectal tumor markers combined with multi slice spiral CT in diagnosis of colorectal cancer was 100% and the specificity 91.25%, and it had statistically differences compared with healthy controls and benign colorectal lesion group (P<0.05). Conclusion The combined detection of tumor markers with multi-slice spiral CT could be helpful in differential diagnosis of colorectal cancer.