Objective To compare the change in liver function, cholinesterase (ChE) and albumin (Alb) between the old and young patients with hepatocellular carcinoma (HCC) before and after microwave ablation (MWA). Methods Three hundred and forty- three HCC patients with single hepatic lesion admitted in our department from Jan. 2013 to Dec. 2013 were recruited in this retrospective study. The patients were divided into the aged group (>60 years old, n=131) and the young group (≤60 years old, n=212), and all given percutaneous ultrasound guided MWA. Results The white blood cell (WBC) count, and alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TB) levels were significantly increased, while the levels of Alb and ChE were decreased obviously in the aged group after MWA (P<0.01). But for the young group, the WBC count and levels of ALT, AST and TB were remarkably elevated (P<0.01) after the treatment, and that of ChE was raised slightly while that of Alb reduced, though without significant difference when compared with the levels before MWA (P>0.05). The young group had the level of ALT increased more significantly than the aged group (P=0.048), but no such differences were found in other indicators. Conclusion The indicators of liver function are increased in both young and aged HCC patients after MWA. But the levels of ChE and Alb, indicating liver reserve function, are decreased more obviously in the aged group than in the young group, which suggested that the elderly HCC patients have worse liver reserve function.