The invention discloses a transformer temperature control device and method, and solves a technical problem that a conventional transformer is liable to be overheated and then damaged. The device comprises a temperature controller disposed in a transformer housing, an air incoming fan, and an air outgoing fan, wherein the air incoming fan and the air outgoing fan are disposed on the transformer housing. The temperature controller comprises a temperature sensor which detects the temperature of a low-voltage side three-phase pile head, a single-chip microcomputer connected with the temperature sensor, and a relay drive circuit connected with the single-chip microcomputer. The relay drive circuit comprises a relay and a triode connected between the single-chip microcomputer and the relay. One input end of the air incoming fan and one input end of the air outgoing fan are respectively connected with a normally opened end of the relay, and the other input end of the air incoming fan and the other input end of the air outgoing fan are respectively connected to a zero-phase pile head. A pile head of any phase of the low-voltage side three-phase pile head is connected with a public end of the relay.