The invention relates to engine waste heat utilization technologies, in particular to a waste heat recycling and reusing system. The waste heat recycling and reusing system comprises a draught fan, a silencer, a heat exchanger and a fuel heater. An exhaust gas cavity is arranged in the middle of the silencer, and engine exhaust gas can enter and come out of the exhaust gas cavity. A heating cavity is formed between the outer wall of the exhaust gas cavity and the inner wall of the silencer. The draught fan is used for providing cold air for the heating cavity. Hot air heated by the heating cavity is used for providing a heat source for the heat exchanger and the fuel heater. According to the waste heat recycling and reusing system, through the improvement on the structure of the silencer, the engine exhaust gas can be directly fed into the exhaust gas cavity, the waste heat of the exhaust gas is used for heating the air in the heating cavity, and the heating speed is high; on the one hand, the heated hot air provides the heat source for the heat exchanger, and hot air is supplied to a cab; and on the other hand, the heated hot air provides the heat source for the fuel heater, and the fuel heating function is achieved.