The invention relates to a synergic-purification all-heat-recovery combined heat and power generation system which comprises a heat power plant waste heat utilization system and a heating station, wherein the heat power plant waste heat utilization system is connected with the heating station through a heat supply network return water supply pipeline; and the heat power plant waste heat utilization system comprises an air humidifier, a gas-water thermal tower, a water-to-water heat exchanger, an absorption heat pump, a steam-to-water heat exchanger and a steam condenser. In the heat power plant, the air is humidified to enhance the dew-point temperature of flue gas; the return water temperature is further lowered in the heating station, so that the heat supply network return water is lowered to 10 DEG C and even lower; and the two measures are integrated to recover all the flue gas waste heat and dead steam waste head. Meanwhile, a dosing port is arranged on a flue gas waste heat recovery spray water path, so that the flue gas is cleaned in the waste heat recovery process, thereby achieving favorable denitrification effects. The acidic condensation water is neutralized to achieve the discharge standard, thereby integrating the functions of waste heat recovery and flue gas purification. The synergic-purification all-heat-recovery combined heat and power generation system is suitable for combustible gas heat power plants, biomass heat power plants and the like, and can be further popularized to coal-burning heat power plants and boilers.