Three-stage filtering device of flue gas monitor

The utility model relates to the technical field of filtering devices of flue gas monitors. The invention further discloses a three-stage filtering device of the flue gas monitor. Filter box, a sealing plug is fixedly mounted on the right side of the filtering box; the right side of the filtering box is communicated with an air inlet pipe with one end penetrating through the sealing plug; three limiting grooves are formed in the left side wall of an inner cavity of the filter box; and three placing holes are formed in the right side wall of an inner cavity of the filter box, an activated carbon layer, a filter screen and a filter plate are movably mounted on the sides, opposite to the three placing holes, of the three limiting grooves correspondingly, the filter plate is located above thefilter screen, and the filter screen is located above the activated carbon layer. According to the three-stage filtering device of the flue gas monitor, the inserting block is drawn out to leave the placing hole, the tension