The invention relates to a method for electrocatalytic reduction of CO2 using multi-metal oxygen cluster ionic liquid as electrocatalyst. The method is characterized in that positive ions of the multi-metal oxygen cluster ionic liquid are imidazoles [Cnmim]+(n=2, 4, 6, 8), pyridines [Cnpyr]+(n=2, 4) and quaternary ammonium salts [N4444]+, and negative ions of the multi-metal oxygen cluster ionic liquid are phosphotungstic acid negative ions (PW12O403-) and phosphomolybdic acid negative ions (PMo12O403-); and the electrocatalytic reduction reaction is a three-electrode system, wherein a glassy carbon electrode is a working electrode, a platinum sheet electrode is a counter electrode, and a saturated calomel electrode is a reference electrode. The method is simple in process and convenient in operation, performs the electrocatalytic reduction for the CO2 to form such fuels as methane and carbon monoxide, realizes the resource utilization of the CO2, reduces the atmospheric pollution, and has important significance on the environmental protection.