Objective To investigate the value of multi-slice spiral CT (MSCT) in the differential diagnosis of liver metastases and primary liver cancer. Methods 38 patients with primary liver cancer and 30 patients with liver metastases were examined by MSCT and whole-liver CT perfusion imaging, and imaging findings of different lesions were observed. The CT enhancement time and CT perfusion parameters of different regions of the liver were compared between different lesions. Results The imaging findings of 38 patients with primary liver cancer showed that there were 28 patients with single lesion and 10 patients with multiple lesions, lesions were round or quasi-circular, showing an expansive growth. After enhanced scan, there was inhomogeneous enhancement in 22 cases, homogeneous enhancement in 11 cases and no enhancement in 5 cases. Among 30 patients with liver metastases, there were 10 patients with single lesion and 19 patients with multiple lesions, the lesion was diffuse type (rain pattering on sand beach type) in 1 case, most of lesions were round or oval. Enhanced scan showed inhomogeneous enhancement in 18 cases, homogeneous enhancement in 10 cases and no enhancement in 2 cases. In terms of CT enhancement time, the initial time of enhancement, time to peak and initial disappearance time of primary liver cancer were significantly shorter than those of liver metastases, while the duration was significantly longer than that of liver metastases (P<0.05). For CT perfusion parameters, the hepatic artery perfusion (HAP) and hepatic perfusion index (HPI) of primary liver cancer were significantly higher than while the portal vein perfusion (PVP) was significantly lower than those of peritumoral tissues and normal liver tissues (P<0.05). The HAP and HPI of liver metastases were significantly higher than those of normal liver tissues while PVP was significantly lower than that of normal liver tissues (P<0.05). The PVP of peritumoral tissues in patients with promary liver cancer was significantly higher than while the HPI was significantly lower than that of the peritumoral tissues in patients with liver metastases (P<0.05). Conclusion MSCT dynamic contrastenhanced scan and CT perfusion parameters are of great value in the differential diagnosis of primary liver cancer and liver metastasis.