OBJECTIVE To investigate the protective effect and mechanism of quercetin on the cardiac and renal functions of rats with cardiorenal syndrome （CRS） based on the phosphoinositide 3-kinase （PI3K）/protein kinase B （Akt）/nuclear factor kappa- B （NF-κB） signaling pathway. METHODS CRS model of SD rats was induced by left anterior descending coronary artery ligation combined with acute renal ischemia-reperfusion. Model rats were randomly separated into model group， quercetin low-dose group （35 mg/kg）， quercetin high-dose group （70 mg/kg）， high-dose of quercetin+740Y-P group （70 mg/kg quercetin+3.5 mg/kg PI3K/Akt/ NF-κB signaling pathway activator 740Y-P）， with 12 rats in each group. Another 12 normal rats were selected as sham operation group. They were given relevant drugs， once a day， for 14 consecutive days. After administration， the cardiac function indexes [left ventricular ejection fraction （LVEF）， end-diastolic volume （EDV）， isovolumic relaxation time （IVRT）] and renal function indicators [blood urea nitrogen （BUN）， 24-hour urine protein， and serum creatinine （Scr）] were detected， and fibrosis in the cardiac and renal tissues was observed； the levels of inflammatory indexes [interleukin-1β （IL-1β） and tumor necrosis factor-α （TNF-α）] in the serum and cardiac and renal tissues as well as the expression of PI3K/Akt/NF-κB pathway-related proteins in the cardiac and renal tissues were detected. RESULTS Compared with sham operation group， the levels of BUN， 24-hour urine protein and Scr， collagen volume fraction of cardiac and renal tissues， the levels of IL-1β and TNF-α in serum and cardiac and renal tissues， and the phosphorylation of PI3K， Akt and NF-κB p65 protein in cardiac and renal tissues were increased significantly in model group （P＜0.05）； the levels of LVEF， IVRT and EDV were reduced significantly （P＜0.05）. Compared with the model group， the above indexes were reversed significantly in quercetin low-dose and high-dose groups （P＜0.05）， and the reversal effect was better in the high-dose group （P＜0.05）. 740Y-P restored the reverse effect of high-dose quercetin on the indexes （P＜0.05）. CONCLUSIONS Quercetin can alleviate cardiac and renal fibrosis and function injury， the mechanism of which may be 20232016） associated with inhibiting the activation of the PI3K/Akt/NF-κB signaling pathway.