The invention provides a hot water recirculation system for waste heat recovery of flue gas, and belongs to the technical field of thermal power energy conservation. The hot water recirculation systemis characterized in that heaters and a flue gas waste heat recovery heat exchanger are connected in parallel to access an adjusting valve; a gate valve and a booster water pump are additionally arranged, and the adjusting valve ensures that condensed water flow entering the flue gas waste heat recovery heat exchanger when an extracting and condensing steam turbine is operated under the steam extraction working condition is stable; a bypass valve is arranged at the booster water pump, the booster water pump does not operate when the steam turbine is in a pure condensing condition, the bypass valve is opened, the system relies on the unit condensation water pump margin to form an open cycle, the power consumption of the system can be reduced, and the power supply coal consumption is reduced; and after the flue gas waste heat recovery heat exchanger is added, an air heater is additionally arranged, so that the flue gas waste heat recovery system realizes multiple modes of operation, theload regulation range is large, and the unit adaptability is good. According to the hot water recirculation system, the waste heat recovery rate of the smoke exhaust is improved, the initial investment of the equipment is reduced, the adjustment is flexible, the energy-saving effect is remarkable, and the engineering implementation difficulty is reduced.