The utility model provides a novel light -gas gun downhole explosion device, including the bangalore, the outside of bangalore is provided with confined bangalore shell, and the bangalore shell is forcan beat open architecture, and the upper end of bangalore intercommunication has the air duct, and the upper end of air duct extends the outside of bangalore shell, and is provided with the valve onthe air duct, and the blasting unit sets up in the outside of bangalore shell, and the ignition of blasting unit end sets up in the bangalore, and the blasting unit is connected with the ignition endthrough the wire. It has the complexity operation of water cannon hole, storage space stringency to aim at solving, and reduce by a wide margin that explosive blasting back produces raise soil, toxicgas scheduling problem in a large number. The utility model belongs to the technical field of the blasting.