Tyrosinase(Tyr) was stably immobilized on the glassy carbon electrode modified with functional graphene oxide(GO) with ethylenediamine as arm molecule.The physical and chemical behaviors of Tyr immobilized on functional GO were characterized by X ray photoelectron spectrum and electrochemical impedance spectroscopy,which demonstrated that functional GO could facilitate the electron exchange between the active center of Tyr and modified electrode.The direct electrochemistry and electrocatalysis behaviors of Tyr on the modified electrode were characterized by cyclic voltammetry,which indicated that Tyr immobilized on the modified electrode displayed a direct and adsorption-controlled redox reaction.Under the optimum conditions,the oxidation current was proportional to hydroquinone(HQ) concentration in the range of 3.0-200.0 μmol/L with correlation coefficient of 0.999 5 and detection limit(S/N=3) of 1.0 μmol/L.Moreover,the proposed electrochemical biosensor also exhibited a good reproducibility，stability and selectivity，and was used to detect HQ in real water samples with satisfactory results.