The invention discloses a box-type transformer station air circulation cooling and dehumidifying system characterized by comprising an automatic control dehumidification device, a first temperature sensor, a second temperature sensor and a blower fan, wherein the automatic control dehumidification device comprises a controller and a dehumidifier connected with the controller; the controller is connected with the first temperature sensor, the second temperature sensor and the blower fan; and the controller, when detecting that the difference of the ambient temperature inside and outside the box-type transformer station detected by the first temperature sensor and the second temperature sensor is greater than a preset temperature difference, starts the blower fan so that the blower fan inhales the air outside the box-type transformer station into the air inlet of the dehumidifier and mixes the air with the air to be dehumidified at the air inlet of the dehumidifier. In addition, the invention also discloses a box-type transformer station air circulation cooling and dehumidifying method. The box-type transformer station air circulation cooling and dehumidifying system and method save energy and the improve dehumidification efficiency.