The invention discloses an automatic transformer winding insulation resistance and medium loss detection device. The device comprises a main controller, and a power source module, a rectification module, a voltage measurement module and a current measurement module which are connected with the main controller, multiple built-in electronic switching switches, four high voltage output interfaces, four current output interfaces and one low voltage output interface, wherein the multiple built-in electronic switching switches are correspondingly connected with the four high voltage output interfaces, the four current output interfaces and the one low voltage output interface, and switching detection on a wiring mode is carried out through controlling on and off of the corresponding built-in electronic switching switches by the controller. According to the automatic detection method, wiring can be unchanged, only through changing output voltage types (AC or DC) and test methods (insulation resistance or dielectric loss), dielectric loss test and insulation resistance test switching can be realized, and performance identical to a single function device is realized.