The invention relates to a gas and dust collecting device, comprising hole sealing components, collecting components and base components which are sequentially connected, wherein the hole sealing components and the collecting components are of hollow structures for accommodating drill pipes. The hole sealing components comprise hole sealing barrels, hole sealing capsules, pieces for fixing the inner sides of the capsules, pieces for fixing outer sides of the capsules, hole sealing flange plates, pipelines in the plates, an externally connected pipeline and hole sealing end covers; the collecting components comprise collecting barrels, a dustproof water pipe, an air water slag outlet pipe and a fixed flange; and the base components comprise a base, sealing ring seats, sealing ring end covers, linings and combined sealing rings. The gas and dust collecting device provided by the invention has the beneficial effects that the phenomenon of ultralimit or continuous deterioration of work environment, caused by the condition that gas or boring mud and dust which are ejected from a drill hole enter an underground tunnel, is avoided.