Objective To investigate the effect and mechanism of Breviscapine (Bre) on posterior circulation ischemic vertigo (PCIV).Methods 80 Wistar rats were randomly divided into sham group, model group, Bre group (2 mg/kg), TAK242 ［toll-like receptor 4 (TLR4) inhibitor］ group (3 mg/kg) and Bre+TAK242 group (2 mg/kg+3 mg/kg), n=16.The PCIV rat models were established by ligating the right common carotid artery and right subclavian artery, and the drugs were given by intraperitoneal injection (ip) once a day for 7 days. The latency to escape from electrical stimulation, blood flow of vestibular nerve nucleus and hemorheological indexes were measured; the pathological changes and apoptosis of hippocampal neurons were observed by HE staining and TUNEL staining; the content of lactate (Lac), lactate dehydrogenation (LDH) and inflammatory factors (IL-1β, TNF-α, IFN-γ) in hippocampus were detected by colorimetry; the protein expression of TLR4, nuclear factor κB p65 (NF-κB p65), phosphorylated NF-κB p65 (p-NF-κB p65), IκBα, p-IκBα were detected by Western blot.Results Compared with the PCIV group, the escape latency in Bre group and TAK242 group were shortened and the vestibular nucleus blood flow were increased (P＜0.05); the whole blood viscosity (low shear, medium shear, high shear), plasma viscosity, hematocrit (HCT), erythrocyte aggregation index (EAI), erythrocyte sedimentation rate (ESR) were decreased and the erythrocyte deformability index (EDI) was increased (P＜0.05); the pathological changes of hippocampal neurons such as the numbers decreased, the arrangement was loose and disordered, the pyknotic pyknosis was shifted and hyperchromatic, the boundary was unclear and other pathological changes were significantly improved; the number of apoptotic hippocampal neurons were significantly decreased; the content of Lac, LDH, IL-1β, TNF-α, IFN-γ in hippocampus were decreased, the expression of TLR4 and the phosphorylation ratio of NF-κB p65, IκBα (p-NF-κB p65 /NF-κB p65, p-IκBα/IκBα) were decreased (P＜0.05) The effect of Bre+TAK242 on the detection indexes above were significantly better than that of Bre group and TAK242 group (P＜0.05)Conclusion Bre can reduce vertigo symptoms, improve vestibular nucleus blood flow and reduce brain tissue damage in PCIV rats, whose mechanism may be related to the inhibition of TLR4/NF-κB signaling pathway to mediate inflammatory responses