The invention relates to a broadband testing device of a B-H characteristic curve of a magnetic material. The testing device is composed of an excitation signal generating circuit, a magnetic material testing circuit, a display circuit, a power supply module and an MCU. The excitation signal generating circuit consists of a DDS module, a signal conditioning module, a sawtooth wave generating circuit, a pulse width modulation circuit, a full-bridge driving circuit, an inverter circuit and an LC filter circuit. The magnetic material testing circuit includes a magnetic material, a current sampling circuit, an RC integral conversion, and a high-speed AD acquisition circuit. The MCU controls the DDS module to generate a sinusoidal signal; and the power supply module provides power for the MCU and the inverter circuit. According to the invention, an excitation signal is generated by using the full-bridge inversion circuit in SPWM signal control; and the output display is improved and thus the display becomes visual. Moreover, the testing device has advantages of reliable testing precision, stable operation, small size, visual output, convenient operation, and low price and the like.