Ginsenoside Rg3 is an active saponin isolated from ginseng, which can reduce renal inflammation. However, the role and mechanism of Rg3 in diabetic kidney disease (DKD) are far from being studied. The effects of Rg3 and miR-216a-5p on the proliferation, apoptosis, and MAPK pathway in high glucose (HG)-induced SV40 MES 13 were monitored by CCK-8, TUNEL staining, and western blot. Rg3 treatment could accelerate proliferation and suppress apoptosis in HG-induced SV40 MES. Moreover, miR-216a-5p inhibition also could alleviate renal injury, prevent apoptosis, and activate the MAPK pathway in kidney tissues of diabetic model mice. Rg3 could attenuate DKD progression by downregulating miR-216a-5p, suggesting Rg3 and miR-216a-5p might be the potential drug and molecular targets for DKD therapy.