The invention relates to a wideband large-dynamic-range automatic gain control circuit of power line carrier communication. The control circuit comprises an impedance match circuit, a bandwidth filtering circuit, a power attenuator, an overload protection circuit, a first detector, a threshold determining device, a changeover switch, an electric adjustable attenuator, an amplifier, a second detector, a proportion integration amplifier and a gain distributer. Via the wideband large-dynamic-range automatic gain control circuit of power line carrier communication, automatic switching is implemented to meet to the requirement of adaptive large-dynamic-range signal input, a determining threshold is changed according to output so that repeated overturn switching is avoided, a circuit realization structure is simple, the dynamic range of the signal amplifier is widened, frequency response is much better than that of a grounded emitter amplifier, the broadband power line carrier signal amplification requirement is met, and the dynamic range of gain adjustment is widened.