The multi-potentiality of mesenchymal stem cells makes them excellent options for future tissue engineering and clinical therapy, including liver injury. In this study, we investigated the effects of valproic acid (VPA), a direct inhibitor of histone deacetylase (HDAC), on the hepatic differentiation of human bone marrow mesenchymal stem cells (BMMSCs). The cells were found to differentiate into a more homogeneous hepatocyte-like population when pretreated with 5 mM VPA for 72 h. The expression of liver-specific markers was significantly upregulated in the VPA-treated group at the mRNA and protein levels. VPA treatment also significantly enhanced the hepatic functions of the differentiated cells, including glycogen storage, cytochrome P450 activity, AFP and ALB synthesis, and urea production. Further analysis showed that treatment with 5 mM of VPA for 72 h greatly improved the histones H3 and H4 acetylation. These results demonstrated that VPA could considerably improve the hepatic differentiation of human BMMSCs, probably because the chromatin-acetylated state changes upon VPA treatment through its HDAC inhibitory effect. Thus, this study provides a direct research model for producing human hepatocytes for clinical purposes.