Abstract: The method of preparing novel poly N,N-dimethyl aniline(PDMA)/multi-walled carbon nanotubes(MWNT) composite film modified glassy carbon(GC) electrode was investigated.SEM and electrochemical characterizations indicated that the morphology and electrochemical performance of the PDMA film were changed no matter the MWNT was doped or drop coated to DMA.The composite film modified electrode greatly increased the specific surface area and the electrical activation area compared with a single PDMA film modified electrode,indicating that the PDMA and MWNT play important roles in improving the electrochemical properties.The results showed that the electrochemical response of vanillin is much greater on the PDMA/MWNT/GC layers than on the bare GC electrode and other modified electrodes.The over potential was reduced by 148 mV,and the oxidation peak current was increased by about six times.The electrode reaction was an irreversible redox process and was likely an adsorptive process.The numbers of the electron and proton transferred in the electrode reaction were 2 and 1,respectively,the transfer coefficient was calculated to be 0.4062,and the amount of adsorption was 3.527 × 10^-9 mol/cm².The detection limit was 8.0 × 10^-7 mol/L,and the average recovery was 99.87%.