OBJECTIVE To investigate the improvement effects and its mechanism of Bazheng powder on chronic urinary tract infection （CUTI） induced by Escherichia coli in rats. METHODS The rats were divided into normal control group， model group， levofloxacin group （45 mg/kg） and Bazheng powder group （4.95 g/kg）， with 10 rats in each group. Except for the normal control group， other groups were administered an intravesical injection of Escherichia coli suspension （1×10⁸ cfu/mL） via the urethra to establish CUTI model； at the same time， rats in each group were administered the corresponding medicinal solution or water by gavage once a day for 4 consecutive weeks. After the last medication， blood routine tests （white blood cell count and lymphocyte percentage）， the levels of serum inflammatory factors [interleukin-1β （IL-1β）， IL-6， IL-8， tumor necrosis factor-α （TNF-α）]， and immune indicators [CD4， CD8， secretory immunoglobulin A （SIgA）]， renal function indicators [cystatin C （Cys-C）， α1- microglobulin （α1-MG）， urea and creatinine] were all determined； the pathological changes in renal and bladder tissues in rats were observed. The protein expressions of Toll-like receptor 4 （TLR4）， nuclear factor-κB （NF-κB）， and nucleotide-binding domain leucine-rich repeat and pyrin domain-containing receptor 3 （NLRP3） in rat bladder tissues were detected. RESULTS Compared with the normal control group， the levels of IL-1β， IL-6， IL-8， TNF-α， CD8， Cys-C， α1-MG， urea and creatinine in serum， as well as the protein expressions of TLR4， NF-κB and NLRP3 in bladder tissues， were significantly elevated in the model group （P＜0.05）. Conversely， the levels of CD4 and SIgA were significantly decreased （P＜0.05）. Pathological changes， such as extensive infiltration of inflammatory cells， were observed in both renal and bladder tissues. Compared with the model group， the above quantitative indicators in the Bazheng powder group were significantly improved （P＜0.05）， with no obvious inflammatory lesions observed in either renal or bladder tissues. CONCLUSIONS Bazheng powder can alleviate inflammatory reaction and improve the immune function of CUTI rats， and its mechanism may be related to the inhibition of TLR4/NF-κB/ NLRP3 signaling pathway.