ObjectiveTo observe the clinical efficacy and safety of Huatan Quyu formula in treating cerebral small vessel disease （CSVD） with phlegm and blood stasis blocking collateral pattern via randomized controlled trial， and explore its mechanism of improving CSVD by regulating glymphatic system （GS） circulation. MethodsSixty-eight CSVD patients with phlegm and blood stasis blocking collateral pattern in the Department of Encephalopathy， Affiliated Hospital of Shaanxi University of Chinese Medicine from April to December 2024 were selected and randomly divided into an experimental group （34 cases） and a control group， with 34 cases in each group. Both groups received basic Western medicine treatment， while the experimental group additionally received Huatan Quyu formula. After a course of 12 weeks， the following parameters were compared between the two groups before and after treatment. Clinical outcomes were assessed using the Tinetti performance-oriented mobility assessment （POMA）， Montreal Cognitive Assessment （MoCA）， Scales for Outcomes in Parkinson's Disease-Autonomic （SCOPA-AUT）， and traditional Chinese medicine （TCM） syndrome scores of phlegm and blood stasis blocking collateral pattern. Perivascular space （PVS） in the frontal lobe/basal ganglia and cerebrospinal fluid （CSF） flow parameters in the cerebral aqueduct were evaluated by 3.0T brain MRI， cerebrospinal fluid flow imaging， and phase-contrast magnetic resonance imaging （PC-MRI）. Then， safety indicators were monitored， and SPSS 25.0 was used for statistical analysis. ResultsSixty-four patients completed the study （32 in each group）. ①Baseline data： No statistically significant difference was found between the two group. ②Efficacy indicators： After treatment， the experimental group exhibited significantly improved total POMA， SCOPA-AUT， and TCM syndrome scores （P<0.01）， outperforming the control group （P<0.05）. No significant change was observed in MoCA scores between the two groups. ③Imaging indicators： The experimental group showed a reduced PVS area alongside significantly increased CSF flow parameters （including downward flow during the systolic period， and upward flow during the diastolic period） （P<0.01）， which were superior to the control group （P<0.01）. ④Safety： The laboratory indicators were normal in both groups， with no drug-related adverse reactions. ConclusionFor CSVD patients with phlegm and blood stasis blocking collateral pattern， Huatan Quyu formula can safely and effectively improve motor function， autonomic nerve function， and TCM syndromes， with potential mechanisms related to pulsatile CSF flow enhancement and GS circulation efficiency improvement.