The invention relates to a device and a method for getting power directly from a high-voltage cable, which is used for getting the electric energy directly from the primary bus current at the high-voltage side through a current mutual inductor. The device comprises a current mutual inductor, a high-voltage protection circuit, a rectifier bridge, an energy release circuit, a voltage stabilization block and a filtering circuit. Since the high-voltage protection circuit is additionally arranged between the current mutual inductor and the rectifier bridge, the induced voltage applied to the rectifier bridge is greatly reduced, the output current of the current mutual inductor is limited, and the invention plays the roles of stabilizing the voltage and the protecting the subsequent circuit andsuccessfully solve the problem of the power supply of the high-voltage side active electronic device.