The invention relates to a deep recycling device for waste heat of boiler smoke. The deep recycling device comprises a boiler, a steam-water heat exchanger, a smoke-water heat exchanger, an air-water heat exchanger and an air reheater. A smoke outlet of the boiler is connected with a smoke inlet of the steam-water heat exchanger, a smoke outlet of the steam-water heat exchanger is connected with a smoke inlet of the smoke-water heat exchanger, an air outlet of the air-water heat exchanger is connected with an air inlet of the air reheater, and an air outlet of the air reheater is connected with an air inlet of the boiler. A water outlet of the steam-water heat exchanger is used for outward overflowing, and the other water outlet of the steam-water heat exchanger is connected with a water inlet of the boiler; a water outlet of the boiler is connected with a water return inlet of the steam-water heat exchanger through a hot net; a water outlet of the smoke-water heat exchanger is used for outward overflowing, and the other water outlet of the smoke-water heat exchanger is connected with a water inlet of the air-water heat exchanger; and a water outlet of the air-water heat exchanger is connected with a water inlet of the smoke-water heat exchanger. According to the deep recycling device, the smoke dew point temperature can be increased, more smoke waste heat can be recycled, meanwhile, the combustion temperature is reduced, and NOx emission is reduced.