The invention discloses a neutral-point direct-current elimination resistance-capacitance device of a transformer. The device comprises four parallel branch circuits arranged in a box body. Besides, a rapid bypass circuit, a capacitor-set and first-resistor series branch circuit, a bypass switch branch circuit, and a second-resistor and mechanical-switch series branch circuit are also arranged. And the box body also includes a current monitor and a digital controller. In addition, the invention also discloses a method for realizing neutral-point direct-current treatment of a transformer by using the device. The method includes the steps that: a digital controller controls turning on or off state of the bypass switch, the rapid bypass loop or mechanical switch by determining whether a numerical value of a current monitor meets a motion requirement, thereby realizing the suppression or elimination effect on the neutral-point direct current of the transformer by the neutral-point direct-current elimination resistance-capacitance device. With the device, under the circumstance that the neutral-point direct-current elimination resistance-capacitance device runs normally or is repaired normally, direct-current biasing processing as well as the direct current and alternating current monitoring function can be realized. Moreover, the scheme is simple and reliable; the maintenance is convenient; and the device is suitable for popularization and application.