The invention relates to a device for eliminating voltage harmonics of a power system, which comprises a harmonic voltage source detection device, a fundamental wave filter, a high frequency transformer, an AC (Alternating Current) power source, a power unit, a rectifying unit, a filtering unit and a controller, wherein the fundamental wave filter is formed by connecting a reactor 1, a reactor 2 and a capacitor in series; the harmonic voltage source detection device collects the real-time harmonic voltage of the system and inputs a harmonic voltage signal to the controller; the controller calculates out a voltage which is equal to the harmonic voltage in magnitude and opposite to the harmonic voltage in direction; the power unit inputs the voltage into an LC (Loop Circuit) branch, formed by connecting the reactors and the capacitor in series, through the high frequency transformer, and the voltage and the harmonic voltage are superposed so that the output harmonic voltage becomes zeroand the effect of filtering out the harmonic voltage in a power grid is achieved; and the controller is connected with the AC power source, the rectifying unit and the power unit respectively. In thedevice, based on the superposition principle, the purpose of eliminating the influence of a power-side higher harmonic voltage source to a load can be achieved by connecting the harmonic voltage sources in series, and the response speed is high.