The invention discloses an integrated structure of an inducer and a capacitor in an EMI wave filter realized through a flexible circuit board, the integrated structure comprises a three magnetic core column closed magnetic circuit. An air gap is arranged on the middle magnetic core column of the closed magnetic circuit, a cylindrical dual-surface flexible circuit board is respectively wound on two side magnetic core columns and is composed of a first insulating layer, a first copper foil, an isolation medium layer, a second copper foil, and a second insulating layer which are overlapped. The first copper foil, the isolation medium layer and the second copper foil of the cylindrical dual-surface flexible circuit board form a common mode capacitor in the EMI wave filter, two cylindrical dual-surface flexible circuit boards form a common mode inductor in the EMI wave filter through a coupling inductor formed by the side magnetic core columns, two cylindrical dual-surface flexible circuit boards form a difference mode inductor in the EMI wave filter respectively through a magnetic circuit composed of the side magnetic core columns and the middle magnetic core column. The integrated structure of the inducer and the capacitor provided by the invention is favorable for decreasing the volume of the EMI wave filter, and improving the power intensity of a power electronic convertor.