To give a preliminary research on diisobutyl phthalate(DiBP) on active avoidance behavior, and the potential of free radical oxidation damage in brain tissues of mice. Methods Accommodating 60Kunming mice to the animal room for 3days, then dividing the mice into 5groups according to their weights including one control group and four experimental groups were 50,0, 500and 1000mg/kg BW. The mice were fed with corn oil in control group, and the other groups were fed with different dose of diisobutyl phthalate mixture by gavages last for 8weeks. At the end point, active avoidance response was examined, then all mice were sacrificed and biomarkers in the brains, such as SOD, GSH-Px and 8-OHdG were testeds.[WT5"HZ]Results In the active avoidance response test, the mice of groups 500and 1000mg/kg BW showed longer response latency than control group(P<0.05) and the mice of group 1000mg/kg BW showed fewer conditioned response than control group(P<0.01); the mice of groups 500and 1000mg/kg BW showed a lower conditioned response rate than control group(P<0.05); the GSH-Px activities in groups 250and 1000mg/kg BW significantly decreased (P<0.05), and the 8-OHdG content increase significantly comparing to the control group, (P<0.05). [WT5"HZ]Conclusion Exposure to DiBP could decrease active avoidance ability. Oxidative stress could be induced by DiBP in mice brain tissue.