Multi-walled carbon nanotubes(MWNT) were doped to modify polybromocresol green film(PBG),and four kinds of modified electrodes were prapared by different modification methods.The modified electrodes were characterized by scanning electron microscopy,AC impedance and cyclic voltammery.The results indicated that the electrical activation areas were increased significantly at the four kinds of modified electrodes,in which the polybromocresol green film/multi-walled carbon nanotube composite film(PBG/MWNT/GC) electrode was the best one to develep the electric activity of MWNT and PBG.The electrode was applied in the study of the electrochemical behavior of 8-hydroxyquinoline(8-HQ),and the voltammetric response of 8-HQ on the four modified electrodes were improved significantly.Among them,the potential of oxidation peak of 8-HQ on PBG/MWNT/GC was shifted negatively and its peak current was the largest(about 4.5 times on that of the bare glass carbon electrode),indicating that the electric catalysis of 8-HQ on PBG/MWNT/GC was largely enhanced.The reaction of 8-HQ on PBG/MWNT/GC electrode was adsorption-controlled irreversible electro-oxidation process,and its numbers of electron transfer and proton were both 1.A good linear relationship was observed between peak current and concentration of 8-HQ in the range of 4.0×10-6-3.5×10-4 mol/L(r=-0.997 2) with a detection limit(S/N=3) of 1.96×10-8 mol/L.PBG/MWNT/GC is avaible to determine 8-HQ quickly and easily.