To investigate the effect of naringin on renal fibrosis in diabetic nephropathy mice and its′ specific mechanism.C57BL/6 mice (n=32) were randomly divided into normal group,diabetic nephropathy group,naringin group and fasuldil group.After the successful establishment of diabetic nephropathy (DN) model,the naringin group mice were given naringin suspension by gavage,the fasuldil group mice were given fasudil by intraperitoneal injection,simultaneously,the normal and diabetic nephropathy group were given isopyknic normal saline.After 12 weeks of intervention,all mice were sacrificed and the level changes of serum creatinine (Scr),24-hour urinary protein (24 h Upro),blood glucose and body weight were observed.HE and Masson staining were used to observe renal morphological changes.The protein expressions of RhoA,ROCK1,ROCK2,type-I collagen (Col1) and type-III collagen (Col3) in renal tissues were tested by immunohistochemical(IHC) staining.And Western blot was applied to detected the protein levels of RhoA,ROCK1,ROCK2,p-MYPT1,Laminin (LN),Fibronectin (FN) in renal tissue.HE and Masson staining showed a little collagen fiber in the renal interstitium of normal group,a large amount of collagen fiber in diabetic nephropathy group and a small amount of collagen fiber in naringin and fasuldil group.Compared with normal group,the levels of 24 h Upro and Scr were increased in diabetic nephropathy group(P<0.05);Compared with diabetic nephropathy group,the levels of 24 h Upro and Scr were decreased in naringin and fasuldil group(P<0.05).However,no statistically difference in blood glucose and body weight between the treatment groups and diabetic nephropathy group was observed (P>0.05).Compared with the normal group,the protein levels of RhoA,ROCK1,ROCK2,Col 1,Col 3,p-MYPT1 Thr853,LN and FN were increased in the diabetic nephropathy group (P<0.05);And compared with the diabetic nephropathy group,these protein levels were markedly decreased in the naringin and fasuldil group(P<0.05).In addition,there was no statistically significant difference in each index between naringin and fasuldil group.Naringin could ameliorate the renal fibrosis in DN mice,which is possibly related to the down-regulation of RhoA/ROCK signaling pathway.