The utility model relates to a flue gas flying ash sampling device which comprises a sampling tank with a transverse gas inlet, a folded plate type separator which is arranged in the sampling tank and is used for separating flying ash from air, a positioning plate sleeving the sampling tank, a connection pipe communicated with the upper end of the sampling tank, a filter communicated with the connection pipe and an extraction device which is connected with the filter and is used for guiding the flowing direction of air in the sampling tank, wherein the sampling tank is of a structure with a closed bottom and an opened upper end. When the flue gas flying ash sampling device is used for sampling, air is guided by an extraction pump when meeting the wall of the tank; soot falls off, and air rises up; the plate type separator further stops soot in air, and the extraction pump continuously works, so that icing in the connection pipe in winter can be prevented.