The invention provides a waste heat utilization device of an engine. The waste heat utilization device comprises an engine, a cooling water circulating pipeline, an engine gas inlet tube, an engine gas outlet tube, a turbocharger, a cooling water tank and a fan, and further comprises a heat exchanger arranged on the cooling water circulating pipeline and a water-cooling intercooler arranged on the engine gas inlet tube as well as an electromagnetic clutch for controlling the fan to open and close, a first temperature sensor and a central controller, wherein a heat-exchange circulating pipeline is connected with a circulating water tank, a circulating water pump, the heat exchanger, the water-cooling intercooler and a heating terminal, and then returns into the circulating water tank; and a liquid level meter, a water replenishing tube and a water pump are arranged in the circulating water tank. The waste heat utilization device of the engine is simple in structure, is high in waste heat recovery efficiency; and compared with a conventional device in which an engine cooling system and a waste heat utilization system are connected in parallel, the waste heat utilization device has the advantages of a simple structure, low cost and a high waste heat utilization rate, is especially suitable for special requirements of power generators used in armies and armies in cold plateau zone to provide heating to barracks.