The invention discloses a variable capacitor circuit used for a smart power grid and a realization method, and relates to the power electronic control field. The circuit comprises a three-phase H bridge main circuit, a direct current side capacitor branch and an alternating current side energy storage branch, wherein the three-phase H bridge main circuit comprises a first bridge arm, a second bridge arm and a third bridge arm which are connected in parallel in sequence; each of the first bridge arm, the second bridge arm and the third bridge arm comprises a switching device separately; the first bridge arm is connected with a wire inlet end c<1>, and a wire inlet end inductor L<1> is connected between the wire inlet end c<1> and the first bridge arm; the direct current side capacitor branch comprises a direct current side capacitor C connected with the three-phase H bridge main circuit in parallel; the alternating current side energy storage branch comprises an alternating currentside capacitor C and an alternating current side inductor L<2> connected in series; the alternating current side energy storage branch is connected between the second bridge arm and the third bridge arm, and connected with the wire outlet end c<2>; and the direct current side capacitor C and the alternating current side capacitor C are both non-electrolytic capacitors. The direct current side capacitor adopts the non-electrolytic capacitor, so that the size of the variable capacitor is reduced, and the service life of the variable capacitor is prolonged.