The invention discloses a dual-gas co-mining device which comprises a casing pipe, a first oil pipe, a second oil pipe and a bridge plug. During well-drain operation of a coal-bed gas well, perforation is performed on a tight sandstone layer, and the tight sandstone gas production layer or a shale gas production layer and a coal bed gas production layer is packed through the bridge plug; perforation is performed on the coal bed gas production layer; the second oil pipe and the first oil pipe with a sucker rod are sequentially placed into the casing pipe. The coal bed gas production layer is drained through a triple-extraction artificial lifting system, after a coal bed gas reservoir reaches desorption pressure, coal bed gas is annularly exhausted from the first oil pipe and the casing pipe, and gas production is achieved; the second oil pipe is used for performing tight sandstone gas exhaust and mining on the right sandstone layer or performing shale gas exhaust and mining on the shale layer. According to the dual-gas co-mining device, it is ensured that no series flow happens between different production layers, no airlocking happens during gas production, co-mining of dual gases of different buried depths and different gas production mechanisms is achieved, and the gas yield of the coal series gas well is effectively increased, and development economic benefits are increased.