〔Abstract〕 Abstract Objective To investigate the regulatory effect of corticosterone (CORT) pretreatment on the activation of microglia by lipopolysaccharide (LPS) and the inhibitory effect of Biochanin A (Bio A) on microglia activation. Methods The MTT method was used to select the optimal concentrations for LPS, CORT and Bio A on BV2 cells; BV2 cells were divided into 5 groups: Control group, CORT (50 nmol/L) group, LPS (1 μg/mL) group, LPS (1 μg/mL) + CORT (50nmol/L) group, and LPS (1 μg/mL) + CORT (50 nmol/L) + Bio A (5 μmol/L) group; Except for the control group, each group was first incubated with CORT (50 nmol/L) for 2 h, and then each group was co-incubated with the corresponding concentrations of LPS (1 μg/mL) and BioA (5μmol/L) for 36 h; DCFH-DA probe method was used to detect reactive oxygen species (ROS) content; Western blot was used to detect the protein expression levels of inflammatory cytokines,5-hydroxytryptamine(5-HTT), glucocorticoid receptor (GR), mineralocorticoid receptor (MR), NOD-like receptor family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC) and cysteine-aspartic protease 1 (Caspase-1) Results Compared with the CORT (50 nmol/L) and LPS (1 μg/mL) groups, cells in the CORT (50 nmol/L)+ LPS (1 μg/mL) group showed increased cell viability, higher levels of ROS, and increased levels of inflammatory cytokines, NLRP3, ASC, and Caspase-1 protein expression (P<0.05);Compared with the CORT (50 nmol/L) + LPS (1 μg/mL) group, the CORT (50 nmol/L) + LPS (1 μg/mL) + Bio A (5 μmol/L) group showed decreased cell viability, decreased levels of ROS, and decreased protein expression of inflammatory cytokines, NLRP3, ASC and Caspase-1 proteins (P<0.05 ).Conclusion A low dose of CORT pretreatment reinforces LPS-induced BV2 cell activation; Bio A inhibits CORT-pretreated LPS-induced BV2 cell activation. The mechanism of which may be related to the inhibition of NLRP3 inflammasome activation.