A novel type ofFe3O4 nanoparticles modified glass carbon electrode(Fe3O4GCE) was constructed and the electrochemical properties of N-(4-nitro-2-phenoxyphenyl)methanesulfonamide(nimesulide) were studied on the Fe3O4/GCE.In 0.4 mol/L HAc-NaAc buffer solution(pH=5.0),the electrode process of nimesulide was irreversible at bare GCE and Fe3O4/GCE.The Fe3O4/GCE exhibited a remarkable catalytic and enhancement effect on the reduction of nimesulide.The reduction peak potential of nimesulide shifted positively from -0.683 V at bare GCE to -0.625 V at Fe3O4/GCE,and the sensitivity was increased by ca.3 times.Some experimental conditions were optimized.The linear range between the peak current and the concentration of nimesulide was 2.6× 10-6—l.0× 10-4 mol/L(R=0.993)with a detection limit of 1.3 × 10-7 mol/L.This method has been used to determine the content of nimesulide in medical tablets.The recovery was determined to be 96.9％- 101.9％ by means of standard addition method.The method is comparable to UV-Vis spectrometry.