To Analyze the structure and function of Zinc-alpha-2-glycoprotein (ZAG), a highly expressed serum protein in the patients with hepatocellular carcinoma (HCC). The serum proteome of the patients from HCC, liver cirrhosis and healthy donors were separated and identified by two-dimensional electrophoresis and MALDI-TOF-MS. RT-PCR and Western blotting analysis were used to confirm ZAG highly expressed in HCC. Bioinformatics technologies were used to analyze the structure character of ZAG protein. Five differentially expressed proteins were identified. Albumin, Serotransferrin，CD5 antigen-like precursor ( IgM - associated peptide) were down-regulated in HCC, ZAG and Ig gamma-1 chain C region were up-regulated in HCC. Zinc-alpha-2-glycoprotein (ZAG), a lipid mobilizing factor, is a member of the major histocompatibility complex (MHC) class I family of protein. ZAG protein might be a potential serological biomarker for HCC early diagnosis.