Objective To investigate the rare CT enhancement performances of small hepatocellular carcinoma and the reasons. To improve the diagnostic accuracy of small hepatocellular carcinoma(SHCC). Methods The rare CT enhancement performances of 20 patients with SHCC(25 lesions) confirmed by operation and pathology were retrospectively analyzed and were compared with the enhancement performances of typical SHCC. The imaging characteristics were summarized. Results 25 lesions were found in 20 cases. Except 2 lesions showed isodense focuses, the other 23 lesions showed high density focuses in plain CT scan. On contrast- enhanced CT imges, 5 cases showed high density focuses in arterial phase and isodense in portal vein and equilibrium phase. 2 cases showed high density focuses in arterial and portal venous phase and low density focuses in equilibrium phase. 3 cases showed high density focuses in arterial and portal venous phase and edge annular clearance in equilibrium phase. 2 cases showed isodense focuses in arterial phase and low density focuses in portal venous and equilibrium phase.2 cases showed no enhancement in three phase("three low density" lesions). 3 cases showed mild enhancement in arterial phase(less than the liver) with the clear and slight irregular boundary, and it showed low density focuses in the portal venous phase with scattered lower density focuses and low density focuses in equilibrium period. 3 cases were multiple focal original, of which 2 cases had 3 lesions respectively and the lesions showed synchronous enhancement, and 2 lesions in 1 case showed asynchronous enhancement. Conclusion There are various rare CT enhancement performances of small hepatocellular carcinoma. Three phase dynamic CT scan is a reliable diagnostic method in the diagnosis of small hepatic cell cancer.