Objective To construct curcumin pyrazole derivative by the reaction of diketone of curcumin and benzylhydrazine based on the above structure-activity relationship,and to explore its antioxidant activity to provide experimental basis for the development of curcumin antioxidant derivative.Methods Curcumin-N-substituted pyrazole derivative was synthesized from curcumin and benzylhydrazine.The structures of the derivative were confirmed by infrared spectroscopy(IR),nuclear magnetic resonance spectroscopy(1H-NMR,13C-NMR)and LC-MS.The antioxidant activity in vitro of the derivative was evaluated by determination of curcumin and its pyrazole derivative scavenging ability for 2,2-diphenyl-1-picrylhydrazyl(DPPH)free radical and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid(ABTS)free radical.Results Curcumin pyrazole derivative was successfully synthesized.Curcumin and its pyrazole derivative showed good free radical scavenging effects in the range of 4.6-73.6,6.25-100 μg·mL-1,respectively,with a significant dose-effect relationship.The half-maximal inhibition(IC50)values of curcumin and its pyrazole derivatives determined by DPPH method were 14.24,40.37 μg·mL-1,respectively,while the IC50 values of curcumin and its pyrazole derivatives determined by ABTS method were 36.65,19.26 µg·mL-1,respectively.Conclusion The antioxidant activity of β-dione of curcumin was retained through the substitution of the pyrazole ring,and the curcumin pyrazole derivative deserves further investigation as a potential antioxidant.