The invention provides a DC CT replacement device, which comprises an input adjustment module, a control module, a voltage detection module, a rectifier module, a power supply module and an output module. The power supply module provides required power supply to the input adjustment module, the control module and the rectifier module; the voltage detection module collects an output voltage of therectifier module and an output voltage of an uninterrupted DC CT connected to the back end of the output module, carries out A/D conversion on the results and transmits the obtained voltages to the control module; and the control module carries out comparison and analysis on the difference value of the two voltages according to a preset threshold value, controls closing or opening of the output module, receives an adjustment signal output by the input adjustment module, and furthermore, adjusts the output voltage of the rectifier module till reaching the threshold value.