The invention provides a heat energy conversion energy-saving device comprising air energy boilers and an original boiler. A water outlet pipe of the air energy boilers is connected with a water supplementing pipe of the original boiler in a sealed mode, and a water inlet pipe of the air energy boilers is connected with a water return pipe and the water supplementing pipe of the original boiler in a sealed mode. An air inlet pipeline of the air energy boilers is connected with a fume exhaust pipeline and a bypass fume exhaust pipeline of the original boiler in a sealed mode. The air energy boilers work, high-temperature exhaust fume of the original boiler enters the N air energy boilers, becomes cold air after heat exchanging through the air energy boilers and then is exhausted, meanwhile, fine particles in the exhaust fume are filtered out completely in an adsorption mode, supplementary water and return water in the original boiler enter the air energy boilers and become a mixture of high-temperature water and steam, and then the mixture enters the original boiler through the water outlet pipe of the air energy boilers. Exhaust fume temperature of the original boiler can be effectively reduced, and most of the fine particles in the exhaust fume can be filtered out in the adsorption mode. Energy is saved, and besides air pollution is reduced.