The invention discloses a vehicle-mounted transformer comprehensive test system. The system is characterized by comprising an industrial personal computer (IPC), a communication module, a hub conversion plate, a short-circuit impedance short connector, a load switch adjuster, and a comprehensive test device, wherein the IPC carries out data communication with each test device of the comprehensive test device through the communication module; each test device of the comprehensive test device is connected with the hub conversion plate through an internal connection wire; the hub conversion plate is connected with a tested transformer through a test wire; a medium-voltage short-circuit impedance short connector and a low-voltage short-circuit impedance short connector are respectively connected with the medium-voltage side and the low-voltage side of the tested transformer through the test wire; the load switch adjuster is connected with a load switch adjusting device of the tested transformer through the test wire. The comprehensive test system provided by the invention can complete all of the test items by a single connection, thereby avoiding frequent replacement of instruments and connection wires.