Abstract: Objective: To study the mechanism of development in hepatocellular carcinoma by analyzing the methylation patterns of α-fetoproteins(AFP) gene and its expression in human hepatocellular carcinoma cell line.Methods: To analyze the relationship of AFP gene methylation and its expression,the methylation status of the promoter and CpG island of AFP gene was investigated by means of bisulfite-assisted genomic sequencing in HepG2,SMMC-7721 and fibroblasts.AFP gene expression was detected by RT-PCR.Results: AFP gene was found expressed in HepG2 cell line higher,which in SMMC-7721 was high,and in fibroblasts was the lowest.In the promoter area of AFP gene,the methylation level was low in HepG2 cell line,which in SMMC-7721 was high,and in fibroblasts was the highest,especially at the first and the second CG sites.But in the CpG island of AFP gene,the methylation level was high in HepG2 and SMMC-7721 cell line,which in fibroblasts was low,especially at the sixth and the seventh CG sites.Conclusions: The methylation patterns of AFP gene may associated with the level of AFP gene expression,AFP gene silencing is associated with the promoter methylation.