The invention mainly provides a reverse circulation dust sampling drill bit which is mainly used for sampling measurement in a dust monitoring process and early stage drilling and later stage reversecirculation sampling in a coal dust gas content and fixed dust sampling process. The reverse circulation dust sampling drill bit consists of three major parts including an outer wall drill body, a cutting sheet and an inner reverse circulation pipe. A cutter body with a drill wing shape is processed on the outer wall drill body; the inner reverse circulation pipe is put at the inside; the cuttingsheet is embedded in the outer drill body; a drill hole is cut and drilled through the cutting sheet, so that the goal of long-distance hole forming drilling is achieved; an annular space passage is formed between the outer wall drill body and the inner reverse circulation pipe, so that the cooling and the outward flowing of a medium for reverse circulation in the position are ensured; and drill slag is discharged through the inner reverse circulation pipe.