The invention discloses a hot exhaust gas environment-friendly cooling, dedusting and filtering system. The system comprises a barrel, a supporting frame and a water tank. A barrel cover is fixed to the top of the barrel and covers the top of an inner cavity of the barrel, and a drainage pipe body is arranged at the bottom of the barrel. The supporting frame comprises a main supporting plate, side supporting plates are fixed to the top face of the main supporting plate, connecting blocks are fixed to the two side supporting plates, slots are formed in the top faces of the middles of the connecting blocks, conical through holes are formed in the bottom faces of the middles of the slots, the barrel is inserted into the slots in a sleeved mode, a conical part is arranged on the lower portion of the barrel, and the conical part is inserted into the conical through holes in a sleeved mode. The outer side wall of the conical part abuts against the inner side walls of the conical through holes, and the drainage pipe body stretches downwards out of the connecting blocks. Impurities in hot waste gas can be removed, water and the impurities can be separated through the water tank, and meanwhile heat energy of the hot waste gas is subjected to heat exchange to heat water flowing in a heat exchange barrel; thus, under the condition that the temperature of the waste gas is decreased, the heat energy can be used, and the energy saving effect is achieved.