A novel hydrogen peroxide biosensor was constructed based on horseradish peroxidase(HRP) immobilized onto glass carbon electrode(GCE),which was modified with the nanocomposite of gelatin and multi-walled carbon nanotubes(MWCNTs).The electrochemistry and electrocatalysis of the modified biosensor were investigated.A pair of well-defined and nearly symmetrical redox peaks with a formal potential of -0.356 V(vs.SCE) in PBS were observed,which attribute to the direct electron transfer between the entrapped HRP and the electrode.The redox peak current was proportional to scan rate in the range of 20-180 mV/s,indicating that the process was affected by electronic transfer electrode rate control surface of mass transfer process.The electrochemical characteristics of the modified electrode were investigated by cyclic voltammetry.The effects of applied potential,solution pH and interferences on the biosensor were discussed.The results demonstrated that HRP could display an excellent electrocatalytic response to the reduction of hydrogen peroxide.Furthermore,the biosensor exhibited a more sensitive catalytic activity on H2O2 in a hydrophilic ionic liquid,1-butyl-3-methylimidazolium tetrafluoroborate(［BMIM］BF4),than that in PBS buffer.A wide linear response to H2O2 in the range of 2.0×10-7-0.13 mol/L was obtained with a detection limit(S/N=3) of 2.3×10-8 mol/L.The modified electrode exhibited the advantages of good stability,wide linear range and lower detection limit as well as a certain anti-interference ability.