The utility model relates to a double endothermic coal-economizing and environment-friendly boiler belonging to combustion apparatus field to settle with that the smoke discharged by boilers has a high temperature, which is not only a waste of energy, but also non-environment-friendly due to sulfur and dust contained in the high-heat smoke. The utility model is characterized in that a plurality of water pipes are disposed rightward of the boiler to bring the temperature of the discharged smoke down from 350 DEG C to a range from 70 DEG C to 140 DEG C, then the smoke gas is sent to a spray pond by a draught fan and sprayed with lime water to desulfurize, finally the desulfurized smoke gas is discharged to the atmosphere above the spray pond. The utility model has the advantages of conservation of energy and protection of environment, which is applicable to non-pressure hot-water boilers.