【Abstract】Objective To investigate the effect and mechanism of miR2245p on proliferation and apoptosis of diffuse large Bcell lymphoma cells. Methods The expression of miR2245p and SMAD5 mRNA in diffuse large Bcell lymphoma tissues and cells was detected by RTqPCR. The plasmids miRNC, miR12245p mimic, miR2245p inhibitor, and pcSMAD5 were transfected into U2932 cells separately or in combination by Lipofectamine 2000. Cell growth was detected by MTT method. Cell proliferation was detected by clone formation experiments. Apoptosis was detected by flow cytometry. The relative expression levels of cleaved caspase3, Bax, Bcl2, and SMAD5 proteins were detected by Western blotting. Targeting relationships were detected by a dual luciferase report. Results miR2245p was significantly downregulated in diffuse large Bcell lymphoma tissues and cells. Compared with the control group, the absorbance of U2932 cells and the number of cloned cells in the miR2245p mimic group were significantly reduced, the apoptotic rate and the expression of cleaved Caspase3, Bax, and Bcl2 were significantly reduced (P＜001 ). Compared with the control group, the miR2245p inhibitor group significantly increased the absorbance of U2932 cells and the number of cloned cells, the apoptosis rate and the expression of cleaved Caspase3, Bax, and Bcl2 significantly increased (P＜001). miR2245p targeted downregulation of SMAD5. Cotransfection of pcSMAD5 reversed the effects of miR2245p on proliferation and apoptosis of diffuse large Bcell lymphoma cells. Conclusion miR2245p overexpression targets SMAD5 and inhibits proliferation and induces apoptosis of diffuse large Bcell lymphoma U2932 cells.