This is a Phase I/II clinical trial for patients with r/r Non-Hodgkin's Lymphoma relapsed after chimeric antigen receptor T cells infusion. The purpose is to evaluate the safety and efficacy of the treatment with chidamide in combination with decitabine.

Inclusion Criteria:

1. Subjects must have histological confirmation of Non-Hodgkin lymphoma (NHL) and relapsed after chimeric antigen receptor T cells infusion.
2. 18 to 65 years of age.
3. ECOG performance of less than 2.
4. Life expectancy of at least 3 months.
5. Subjects with lymphoma must have at least one measureable new lesion >1.5cm as defined by lymphoma response criteria.
6. Subjects must have relapsed after chimeric antigen receptor T cells infusion without any intervention treatment prior to Day 1.
7. Subjects must have adequate marrow, live, renal and heart functions.

Exclusion Criteria:

1. Subjects with any autoimmune disease or history of syndrome that requires corticosteroids or immunosuppressive medications.
2. Serious uncontrolled medical disorders or active infections, pulmonary infection especially.
3. Active alimentary tract hemorrhage or history of alimentary tract hemorrhage in one month .
4. Prior organ allograft.
5. Women who are pregnant or breastfeeding.
6. Women with a positive pregnancy test on enrollment or prior to investigational product administration.
7. Subjects who are compulsorily detained for treatment of either a psychiatric or physical (eg, infectious disease) illness