HDAC-IN-31 is a potent, selective and orally active HDAC inhibitor with IC 50 s of 84.90, 168.0, 442.7, >10000 nM for HDAC1 , HDAC2 , HDAC3 , HDAC8 , respectively. HDAC-IN-31 induces apoptosis and cell cycle arrests at G2/M phase. HDAC-IN-31 shows good antitumor efficacy. HDAC-IN-31 has the potential for the research of diffuse large B-cell lymphoma.