This is a study to evaluate the efficacy and safety of TQ-B3525 in subjects with relapse/refactory diffuse large B-cell lymphoma who have received at least 2 lines of therapeutic schedules including rituximab. TQ-B3525 tablet administered 20mg orally, once daily in 28-day cycle.

Inclusion Criteria:

• 1.Understood and signed an informed consent form; 2. 18 years and older, Eastern Cooperative Oncology Group(ECOG) performance status score of 0 to 2, Life expectancy ≥ 3 months; 3. Relapsed/refractory Diffuse Large B-cell lymphoma （DLBCL); 4. Has received at least two lines of previous treatment, the latest treatment confirmed no objective response, or disease progress after treatment, either of the treatment should conclude rituximab; 5. Has at least one measurable lesion; 6. Adequate organ system function; 7. Male or female subjects should agree to use an adequate method of contraception starting with the first dose of study therapy through 6 months after the last dose of study (such as intrauterine devices , contraceptives or condoms) ；No pregnant or breastfeeding women, and a negative pregnancy test are received within 7 days before the first administration.

Exclusion Criteria:

• 1. DLBCL transformed from previously diagnosed indolent lymphoma; 2. Has central nervous system violation; 3. Has received other PI3K inhibitors or CAR-T treatments; 4. Has diagnosed and/or treated additional malignancy within 3 years prior to the first administration; 5. Has type I diabetes or uncontrolled type II diabetes; 6.Has history of interstitial lung disease; 7. Has a history of immunodeficiency diseases; 8. Has multiple factors affecting oral medication; 9.Has adverse events caused by previous therapy except alopecia that did not recover to ≤grade 1; 10. Has received systemic steroid treatment within 7 days before the first administration; 11. Has received other systemic anti-tumor medications within 4 weeks before the first administration, or still within the 5 half-life of the medication, which occurs first; 12. Has active infections within 4 weeks before the first administration; 13. Has received surgery, or unhealed wounds within 4 weeks before the first administration; 14. Has a history of autologous hematopoietic stem cell transplant within 3 months; 15. Has a history of allogeneic hematopoietic stem cell transplant; 16. Grade II or higher cardiovascular disease within 6 months before the first administration; 17. QTCF > 480ms, LVEF < 50%; 18. Urinary protein ≥ 2 +, and 24-hour urinary protein quantity>1g within 7 days; 19. Has active hepatitis B or C; 20. Has psychotropic substances abuse or a mental disorder; 21. Has other conditions that make it inappropriate for the patient to be enrolled based on investigator's opinion.