Objective To investigate the therapeutic effect and underlying mechanism of Qishishenshu Capsule on renal fibrosis in mice with early diabetic nephropathy(DN).Methods A DN mouse model was established by multiple injections of streptozotocin.The mice were randomly divided into a normal group(NC),model group(DN),and Qishi group(QS)(0.9 g/(kg·d)),with eight mice in each group.Mice were gavaged continuously for 4 weeks,and fasting blood glucose(FBG)was measured weekly.Four weeks later,urinary albumin/creatinine(UACR),serum creatinine,and blood urea nitrogen were measured.Hematoxylin-eosin,periodicacid-Schiff,and Sirius red staining were used to analyze renal pathological changes.Real-time fluorescence quantitative reverse-transcription polymerase chain reaction was used to detect the mRNA levels of fibronectin(FN),collagen type Ⅰ alpha 1(Col1a1),and α-smooth muscle actin(α-SMA).Immunohistochemistry and Western blot were performed to detect FN,collagen type Ⅰ(Collagen Ⅰ),collagen typeⅢ(Collagen Ⅲ),α-SMA,Podocin,Nephrin,and transforming growth factor-β1/SMAD family member2/3(TGF-β1/Smad2/3)pathway-related proteins.Results Compared with mice in the NC group,those in the DN group showed significantly higher levels of FBG and UACR(P＜0.001),and mesangial hyperplasia,basement membrane thickening,and collagen deposition in the renal tissue.The mRNA levels of FN,Col1a1,and α-SMA were increased(P＜0.05).Protein levels of Podocin and Nephrin were decreased(P＜0.05).The levels of FN,Collagen I,Collagen Ⅲ,α-SMA,and TGF-β1/Smad2/3 pathway proteins were increased(P＜0.05).Compared with the DN group,the QS group's level of UACR was decreased(P＜0.05),their renal pathological injury was alleviated,and mRNA levels of FN,Collagen Ⅰ,andα-SMA were attenuated(P＜0.05);whereas their protein levels of Podocin and Nephrin were elevated(P＜0.05).The levels of FN,Collagen Ⅰ,Collagen Ⅲ,α-SMA,and TGF-β1/Smad2/3 pathway proteins were also decreased(P＜0.05).Conclusions Qishishenshu Capsule improved renal fibrosis in DN mice,probably through the inhibition of the TGF-β1/Smad2/3 signaling pathway.