OBJECTIVE To investigate the effect and mechanism of total flavonoids of Bidens pilosa L. （TFB） on lipopolysaccharide （LPS）-induced neuroinflammation in mice. METHODS Fifty C57BL/6 mice were randomly divided into normal control group， LPS group and TFB low-dose， medium-dose and high-dose groups， with 10 mice in each group. TFB low-dose， medium-dose and high-dose groups were given TFB solution intragastrically at 60， 120 and 240 mg/kg， and the normal control group and LPS group were given corresponding volume of normal saline， once a day， for consecutive 21 d. From the 15th day of administration， except for the normal control group， other groups were given LPS （400 μg/kg） intraperitoneally for 7 consecutive days to establish neuroinflammatory model. Brain tissues were taken under anesthesia 4 h after the final administration. The morphological changes of neuronal cells in mice were observed； the contents of nitric oxide （NO）， tumor necrosis factor α （TNF- α）， interleukin-1β （IL-1β）， IL-6 and IL-10 were measured， and the expressions of inflammatory pathway-related proteins [inducible NO synthase （iNOS）， cyclooxygenase-2 （COX-2）， myeloid differentiation factor 88 （Myd88） and protein kinase C （PKC）] were measured in the brain tissues of mice. RESULTS Compared with the normal control group， the neuronal arrangement in the hippocampal region of the brain tissue of mice in the LPS group was sparsely disorganized， with a large number of neuronal fixations and shrunken nuclei； the contents of TNF-α， IL-1β， IL-6 and NO in the brain tissue were significantly increased， the contents of IL-10 were significantly decreased， and the relative expressions of iNOS， COX-2， Myd88 and PKC proteins were significantly increased （P＜0.05）. Compared with the LPS group， the neuronal pathological changes in the brain tissue of mice in the TFB low-dose， medium-dose and high-dose groups were 202014810） significantly improved， and the changes of the above indices in the brain tissue were significantly reversed （P＜0.05） CONCLUSIONS TFB has an inhibitory effect on E-mail：pangxjun@163.com neuroinflammation， and its mechanism of action may be related to down-regulation of the expressions of inflammatory pathway-related proteins iNOS， COX-2， Myd88 and PKC， and reduction of inflammatory factors release.