Objective To investigate the value of spiral CT threephase dynamic scan and plain scan in the diagnosis of liver cancer. Methods 78 cases of liver cancer confirmed by pathology in 9 menstrual cycles in our hospital were selected as the subjects, to analyze the imaging features of liver cancer during CT noncontrast enhanced scan and three phase enhanced scan, compare the detection rate of the lesions between the two examinations. Results Of the 78 patients, 72 cases were solitary lesions (93.58%), multiple lesions were in 5 cases (6.41%), there were 89 lesions. In 76 patients (97.43%), CT noncontrast enhanced scan showed low density or equal density shadow,the appearance of the shape of a circular or circular shadow. CT phasethree scan results show, in 64 patients (82.05%), the arterial phase lesions increased rapidly, marked by high or equal density, punctate, nodular or flocculent, the lesion persisted with time and diffused toward the center, 48 of them (61.53%) showed homogeneous enhancement, 16 cases (20.51%) were moderately strengthened. 12 patients (15.38%) showed no enhancement, 2 cases (2.56%) were inhomogeneous enhancement. In 61 patients (78.20%), the density of the portal phase decreased rapidly, lower than parenchymal density. The delayed phase showed low density change, presenting typical "fast forward, fast out" imaging findings,The detection rate of CT noncontrast enhanced scan for HCC was 83.14% (74/89), the detection rate of HCC in the three phase enhanced scan was 100% (89/89), the detection rate of CT noncontrast enhanced scan for liver cancer lesions was significantly lower than that of phase three enhanced integrated scan (P<0.001). Conclusion The three phase dynamic scan of spiral CT has high detection rate for liver cancer, which can clearly show the typical image features of liver cancer, and provide reliable imaging data for clinical treatment.