The invention discloses a testing device and a testing method for a silicon steel core limit hysteresis loop. The testing device comprises an autotransformer, a customized core, a primary coil, a secondary coil, a recorder, a current probe, a voltage probe and a current limiting resistor. The primary coil and the secondary coil are wound on two sides of the customized core. A high-voltage end of the autotransformer is externally connected with an alternating current power supply. The primary coil is serially connected with the current limiting resistor and then connected with a low-voltage end of the autotransformer. A jaw type input end of the current probe is clamped on a current loop of the primary coil. An input end of the voltage probe is connected with the secondary coil. An input end of each of the current probe and the voltage probe is connected with a recoding passage of the recorder. The testing device is simple in structure, low in cost, applicable to various experiment institutions and enterprises which need to acquire feature curves of the silicon steel core limit hysteresis loop, and promising in application prospect.