A heat exchanger, comprising: a first air duct and a second air duct, wherein the first air duct and the second air duct are isolated from each other, the first air duct is set with a first heat exchange unit, and the second air duct is set with a second heat exchange unit; characterized in that: the first heat exchange unit comprises: a first heat pipe heat exchanger and an evaporative cooler; and the second heat exchange unit comprises: a second heat pipe heat exchanger and a condensation radiator; a cavity of the first heat pipe heat exchanger is connected to a cavity of the second heat pipe heat exchanger through a first pipeline, so that a first closed loop is formed between the cavity of the first heat pipe heat exchanger and the cavity of the second heat pipe heat exchanger; a cavity of the evaporative cooler is connected to a cavity of the condensation radiator through a second pipeline, so that a second closed loop is formed between the cavity of the evaporative cooler and the cavity of the condensation radiator; and the first closed loop and the second closed loop each contain a fluid capable of carrying heat; and characterized in that, the heat exchanger further comprises: a compressor and a first valve, wherein the compressor is set in the second pipeline through which the fluid flows from the evaporative cooler to the condensation radiator, an inlet of the compressor is connected to the evaporative cooler through the second pipeline, and an outlet of the compressor is connected to the condensation radiator through the second pipeline; and the first valve is set in the second pipeline between the inlet of the compressor and the evaporative cooler; and when the temperature of the first heat pipe heat exchanger side is higher than a first target temperature, the first valve is opened, and the compressor is turned on so that the compressor is in a working state; when the temperature of the first heat pipe heat exchanger side is lower than a second target temperature, the first valve is closed, and the compressor is turned off so that the compressor is in a non-working state, wherein both the first target temperature and the second target temperature are lower than or equal to an ambient temperature needed by a heat source to work normally, and the first target temperature is higher than or equal to the second target temperature. the first heat exchange unit comprises: a first heat pipe heat exchanger and an evaporative cooler; and the second heat exchange unit comprises: a second heat pipe heat exchanger and a condensation radiator; a cavity of the first heat pipe heat exchanger is connected to a cavity of the second heat pipe heat exchanger through a first pipeline, so that a first closed loop is formed between the cavity of the first heat pipe heat exchanger and the cavity of the second heat pipe heat exchanger; a cavity of the evaporative cooler is connected to a cavity of the condensation radiator through a second pipeline, so that a second closed loop is formed between the cavity of the evaporative cooler and the cavity of the condensation radiator; and the first closed loop and the second closed loop each contain a fluid capable of carrying heat; and