The invention discloses a low-quality waste heat recovery power generation device. The low-quality waste heat recovery power generation device comprises a resource recovery system, a power generation system and a water supply system; the resource recovery system comprises a heat tube steam generator, a descending steam pipeline, a steam manifold, an ascending steam pipeline, a flue gas inlet, a flue gas primary path, a flue gas bypass, a coal saver, a flue gas pipeline entering the coal saver and a residual flue gas exhaust pipeline; the power generation system comprises a steam bypass, a steam primary path, a gas storage tank, a root's power machine, a power generator and an electric energy quality monitoring instrument; the water supply system comprises a condenser, a deaerator, a drainage pipeline, a water supply tank, a condensing and supplementing pump, a condenser liquidometer, a water supply pipeline, a condensing pump, a water feeding pump and a deaerator liquidometer. A circulating work medium in the device is water and steam which circulate, a flue gas in a low-quality waste heat resource can be recycled. The device is simple in structure, low in cost and high in utilization ratio of energy sources.