Abstract: Objective To analyze the expression of CD70 in diffuse large B cell lymphoma (DLBCL) and its correlation with clinical prognosis.Methods A total of 116 patients newly diagnosed with DLBCL who were admitted to the First Affiliated Hospital of Bengbu Medical College from January 2017 to December 2021 were selected and their clinical data were retrospectively analyzed. The expression of CD70 in tumor tissues was detected, and the clinical significance of CD70 expression in DLBCL patients was analyzed.Results The positive expression rate of CD70 in 116 DLBCL patients was 80.17%, and its expression was related to mid-term efficacy, B symptoms, bone marrow involvement and Ann Arbor stage (P<0.05). However, CD70 expression was not associated with sex, age, lactate dehydrogenase (LDH), β2-microglobulin (β2-MG), B-cell lymphoma-2(BCL-2), BCL-6, Ki-67, Hans classification, primary site and international prognostic index (IPI) score (P>0.05). Survival analysis showed that the progression free survival (PFS) and overall survival (OS) of the CD70 positive group were significantly higher than those in the CD70 negative group (P<0.05), and the prognosis of CD70 positive patients was worse. According to univariate analysis, the prognosis of DLBCL patients was affected by efficacy, LDH, β2-MG, Ki-67, Hans classification, Ann Arbor stage, IPI score and CD70 expression. Multivariate analysis showed that mid-term efficacy, Ki-67, Hans classification and CD70 were the independent prognostic factors for PFS, and mid-term efficacy, β2-MG、Ki-67、Hans subtype and CD70 were the independent prognostic factors for OS.Conclusions CD70 is highly expressed in DLBCL and strongly associated with poor prognosis.