A light single button multi-function electric hammer comprises a body, a motor, a rotation set assembly, a cylinder assembly, a torque spring, a knob, a gearwheel and a transmission mechanism of torque clutch. The transmission mechanism comprises a pinion, a gear clutch, a middle shaft, a hammer crosspiece clutch, a swing rod bearing and a primary gear. The pinion is movably fitted with the middle shaft; the pinion meshes large end teeth of the gearwheel and matches with the inner teeth of the gear clutch. The gear clutch meshes small end teeth of the gearwheel and is fitted with the teeth shaft of the middle shaft. The gear clutch and the hammer crosspiece clutch are movably fitted with the teeth shaft of the middle shaft. The knob is connected with an operating mechanism linked to the large teeth end of the gearwheel, the gear clutch and the hammer crosspiece clutch.