Objective To investigate the clinical value of spiral CT multi-phase scanning technique in the early diagnosis of rectal cancer. Methods Select 120 cases of rectal cancer diagnosed by our hospital from June 2015 to June 2016, the patients underwent spiral CT multi-phase scan, and collect the imaging data and clinical data,the results of T, N and M in three patients were determined and compared with the pathological results after operation. Results 120 patients were based on pathological findings, and the results of multi-phase helical CT scan showed: The diagnostic coincidence rate of T staging was 90.83% (109/120). The diagnostic coincidence rate of N staging was 67.70% (81/120), and the diagnostic accuracy rate of M staging was 96.67% (116/120). CT scan image is mainly localized soft tissue mass, rectal wall thickening (visible cross-section is circular or semi-circular), lumen narrowing, uniform density. In the enhanced CT scan, the arterial phase showed a thickening of the transverse section and a marked enhancement of the rectal wall, the venous phase showed thickening and persistent enhancement of the rectal tube wall, the delayed period showed that the wall of thickened tube showed persistent enhancement and the wall edema was more obvious. The CT value of the tumor increased obviously after injection of contrast medium. Conclusion Spiral CT multi-phase scanning technique is of high diagnostic accuracy in the early diagnosis of rectal cancer, it can well display the typical imaging features of hepatic hemangioma, and can play a very good guiding role in the development of clinical operation and treatment plan.