The invention discloses a boiler flue gas waste heat recovery system. The boiler flue gas waste heat recovery system comprises a coal economizer, a pump body, a first heat exchanger, a second heat exchanger, a heating network water system and a condensate water system. The coal economizer, the heat exchange medium side of the first heat exchanger and the pump body are communicated sequentially to form a first circulation circuit. The coal economizer, the heat exchange medium side of the second heat exchanger and the pump body are communicated sequentially to form a second circulation circuit. The first water side of the first heat exchanger is communicated with the condensate water system to form a first heat exchange circuit. The second water side of the second heat exchanger is communicated with the heating network water system to form a second heat exchange circuit. According to the boiler flue gas waste heat recovery system, the independent heat exchange of heating network water and condensate water is achieved; the water quality interference phenomenon is effectively prevented; it is ensured that the condensate water of a main machine is not polluted. Meanwhile, the indirect heat exchange mode that heat exchange is conducted between heat exchange media and boiler flue gas is adopted, so that the condensate water and the heating network water do not make contact with the coal economizer directly; the pressure resisting requirement of the coal economizer is lowered; the production cost of raw materials can be reduced.