An electronic load device provided for testing an OT (power supply to be tested) and the working bandwidth is regulated and set according to the output impedance of the OT. The electronic load device comprises a CPU, an impedance-bandwidth table, a voltage-current measurement unit, a power stage and a control module. Firstly, a current pulled out from the OT to the power stage is called by the CPU. Thereafter, an output impedance of the OT is measured by the voltage-current measurement unit and analysis by the CPU. Next, a working bandwidth of the electronic load device is regulated and set by the control module according to the output impedance and the impedance-bandwidth table.