This study was aimed to investigate the effects of valproic acid sodium (VPA) on the proliferation and apoptosis of acute T-lymphoblastic leukemia Jurkat cells. Jurkat cells were treated with different concentration of VPA. Proliferation-inhibition curve was assayed and plotted by CCK-8 method and the cell apoptosis was detected by flow cytometry with Annexin V/PI double staining. The expression level of anti-apoptotic gene BCL-2 and pro-apoptosis gene Bak1 were detected by semi-quantitative RT-PCR. The results showed that the VPA inhibited the proliferation of Jurkat cells in concentration-dependent manner. As compared with the control group, the apoptosis of cells increased along with adding concentration of VPA; VPA could decrease the expression of BCL-2 gene, but did not show obvious effect on the expression of Bak1. It is concluded that the VPA can inhibit proliferation of Jurkat cells which possibly associates with the decrease of BCL-2 expression.