The invention discloses a microchannel plate type composite radioisotope battery. A first radiation source, a first receiving pole, a second radiation source and a second receiving pole are insulating-arranged on an insulating base from left to right, a microchannel plate is arranged between the second radiating source and the second receiving pole, the high-voltage ends of the first radiation source and the mircochannel plate are connected by a wire; the low-voltage ends of the first receiving pole and the microchannel plate are connected by a wire; the second radiation source is used as the anode of the radioisotope battery; and the second receiving source is used as the cathode of the radioisotope battery. The radioisotope battery needs no external energy, the current can reach to muA-mA order, 10<4>-10<8> order higher than common primary radioisotope battery. If a multi-pole microchannel plate is used, the current can be increased further.