Heat exchanger of refrigeration dryer

Disclosed is a heat exchanger of a refrigeration dryer, comprising a pre-cooler (1), an oil remover (2), a condenser (3), and an air return pipe (4). An air inlet layer and an air return layer which are next to each other are provided inside the pre-cooler (1), wherein an air inlet (11) is provided on a front end of the air inlet layer, and the oil remover (2) is connected to a rear end thereof, several oil removing filter screens (21) being provided inside the oil remover (2), and an oil discharge port (22) being provided on a lower end of the oil remover (2). The condenser (3) is provided with an air inlet layer and a refrigerant layer which are also next to each other, wherein a front end of the air inlet layer of the condenser (3) is in communication with the oil remover (2), a rear end thereof is connected to the air return pipe (4), and the refrigerant layer is provided with a refrigerant inlet (31) and a refrigerant outlet (32). A water discharge port (41) is provided on a lower end of the end, which is connected to the condenser (3), of the air return pipe (4), and a filter screen is provided by an upper end thereof, and the other end of the air return pipe (4) is in communication with an air return layer of the pre-cooler (1), and an air discharge port (12) is provided on a rear end of the air return layer. The heat exchanger of a refrigeration dryer saves condensing time and operating costs, removes oils from humid air, and ensures the cleanliness of dry air.