Renal fibrosis (RF) is a common pathological feature of chronic kidney disease (CKD), which remains a major public health problem. As now, there is still lack of chemical or biological drugs to reverse RF. Shen-shuai-yi Recipe (SSYR) is a classical Chinese herbal formula for the treatment of CKD. However, the effects and mechanisms of SSYR in treating RF are still not clear. In this study, the active constituents SSYR for treating RF were explored by UHPLC-Q-Orbitrap HRMS. Bioinformatics analyses were employed to analyze the key pharmacological targets and the core active constituents of SSYR in the treatment of RF. In experimental validation, vehicle or SSYR at doses of 2.12 g/kg/d and 4.25 g/kg/d were given by orally to unilateral ureteric obstruction (UUO) mice. 13 days after treatment, we detected the severity of renal fibrosis, extracellular collagen deposition and pre-fibrotic signaling pathways. Bioinformatics analysis suggested that signal transducer and activator of transcription 3 (STAT3) was the core target and lenticin, luteolin-7-O-rutinoside, hesperidin, kaempferol-3-O-rutinoside, and 3,5,6,7,8,3',4'-heptamethoxyflavone were the key constituents in SSYR for treating RF. SSYR significantly reduced the expressions of fibronectin (FN), α-smooth muscle actin (α-SMA), collagen-I and alleviated renal interstitial collagen deposition in UUO kidneys. In mechanism, SSYR potently blocked the phosphorylation of STAT3 and Smad3 and suppressed the expression of connective tissue growth factor (CTGF). Collectively, SSYR can ameliorate RF inhibiting the phosphorylation of STAT3 and its downstream and reducing the collagen deposition, suggesting that SSYR can be developed as a novel medicine for treating RF.