We focused the role of Chidamide on CD20 expression and related gene expression in DLBCL cell lines and found that 5 μM Chidamide could sufficiently induce the expression of the acetylated histone-H3 expression and reduce the expression of HDAC1, 2, 3, 10 and p-HDAC3 (Ser424), and increase in Chidamide concentration (higher than 5 μM) did not further increase or decrease the expression of these genes. The gene discussed is HDAC1; the disease is diffuse large B-cell lymphoma.