The invention discloses a gradient utilization system for waste heat of high-temperature flue gas exhausted by an industrial boiler. The system mainly includes a high-temperature flue gas power regeneration system, a medium-temperature flue gas refrigerating and heating system and a low-temperature flue gas hot water supply system. According to the system, high-temperature flue gas is directly utilized for gasifying water into vapor in a heat exchanger, then a turbine is pushed to rotate so as to drive a power generator to generate power, and medium-temperature flue gas exhausted out of the high-temperature flue gas power regeneration system can be used for providing heat energy for a heat pump air conditioner system, so that refrigeration is achieved in summer and heating is achieved in winter; and flue gas exhausted out of the medium-temperature flue gas refrigerating and heating system further has considerable heat, and the low-temperature flue gas can be utilized for preheating cold water or cold air in order to provide domestic hot water for people or provide preheated air for the boiler. The system saves energy resources to a great extent and has a remarkable effect on lowering the production cost of large-scale enterprises by fully utilizing original heat exhausted into air.