Most recurrences of diffuse large b lymphoma occur within 2 years of diagnosis. Factors such as pathologic staging, genetic subtype, and risk stratification affect the prognosis, and standardized systemic therapy is recommended. 1. Adult diffuse large B-cell lymphoma (DLBCL) is the most common subtype of lymphoma. About 20% of patients are primary refractory to first-line standard therapy (i.e., treatment is ineffective or relapse occurs within 6 months after treatment), about one-quarter of patients relapse early (i.e., relapse occurs within 2 years after treatment), and some patients relapse late (i.e., relapse occurs after 2 years after treatment). 2. The later the relapse, the better the prognosis. After the use of targeted drugs, the long-term survival rate of DLBCL appears to be significantly improved, about 60% of patients can be clinically cured through standardized treatment, and long-term survival; the remaining part of the patients are relapsed and refractory, and the overall long-term survival is poor. 3. Individualized diagnostic modes such as molecular diagnosis to screen targeted drugs, assisting in the development of individualized combined treatment plans, as well as the emergence of new drugs and therapeutic methods will help the diagnosis and treatment of relapsed and refractory patients. Individualized and precise treatment model based on standardized systemic therapy is the overall treatment strategy for DLBCL recurrence, and regular review is recommended to evaluate the condition.