Objective To study the effect of brain‐derived neurotrophic factor (BDNF) in the process of adenosine triphos‐phate (ATP) activating BV2 microglia .Methods BV2 microglia was cultured by adding different concentrations of ATP .Then the expression level of intracellular CD11b and BDNF and the secretion level of TNF‐α in the supernatant were quantitatively deter‐mined by Western blot .BV2 microglia was treated by different concentrations of BDNF scavenger tyrosine kinase receptors B (TrkB)/Fc and incubated by ATP .The expression level of intracellular CD11b and BDNF and the secretion level of TNF‐αin the supernatant were measured .Finally adding exogenous recombinant BDNF into cultured BV 2 microglia ,intracellular changes of CD11b and supernatant TNF‐αlevels were detected .Results After adding ATP for cultivating BV2 microglia ,intracellular CD11b and BDNF expression levels and supernatant TNF‐αlevel were increased with a dose‐and time‐dependent manner in some ranges . After adding TrkB/Fc ,the levels of intracellular CD11b and BDNF expression and supernatant TNF‐αlevel were decreased with a dose‐and time‐dependent manner in some range .CD11b and BDNF expression levels was decreased in a dose‐and time‐dependent manner .Adding exogenous BDNF ,the levels of intracellular CD11b and BDNF expression and supernatant TNF‐α level were in‐creased again .Conclusion Intracellular BDNF expression is increased when BV2 microglia is activated and replenishing exogenous BDNF can activate microglia .Therefore BDNF may play an important role in the microglia activation process .