The invention discloses a waste heat recovery system for a residential washroom. The waste heat recovery system comprises a drainage pipeline, a water supplying pipeline and a heat exchanging mechanism; a floor drain is arranged at one end of the drainage pipeline, and the floor drain is arranged in a floor of the residential washroom; the water supplying pipeline is used for supplying water for hot water using equipment of the residential washroom; the heat exchanging mechanism is arranged in the floor, and the water supplying pipeline is subjected to heat exchanging through the heat exchanging mechanism; a metal heat exchanging plate is used for being laid on the ground of a showering part of the residential washroom and serves as one part of a shell of the heat exchanging mechanism; andthe water supplying pipeline and the metal heat exchanging plate are subjected to heat exchanging. According to the waste heat recovery system for the residential washroom, the metal heat exchangingplate is arranged on the ground of the residential washroom and serves as a heat exchanging core part of a heat exchanger, in this way, the large heat exchanging area is provided, the size of the heatexchanger is also decreased, and thus a series of problems caused by the excessively large area of the heat exchanger are solved.