There are one third of diffuse large B-cell Lymphoma patients suffering relapse and refractory, which are the major cause of death among these patients. Vinorelbine，liposomal doxorubicin，mitoxantrone, dexamethasone and thalidomide have been used in the therapy of patients who failed with Second-line treatments in our center. This regimen is well tolerated but the effect needs to be improved. Chidamide，a histone deacetylase inhibitor has been approved for the treatment of refractory T-cell lymphoma in China. The goal is to assess the efficacy and safety of chidamide combined with VDDT（vinorelbine，liposomal doxorubicin，dexamethasone and thalidomide） in relapse and refractory patients with diffuse large B-cell Lymphoma.