The integral structure of the common-mode inductance and differential mode capacitor in the EMI electric wave filter realized by the flexible circuit board of the invention comprises a closed magnetic circuit formed by a first magnetic core and a second magnetic circuit, a multilayer parallel flexible circuit board with tube type which is twisted on the magnetic core column of the closed magneticcircuit. The multilayer parallel flexible circuit board with tube type is formed by coiling sheet, wherein the sheet is formed by interactively superposing 2N copper foil layers and 2N-1 insulating medium layers which are located between two insulating layers. The N is positive integer, the heads and the ends of all odd layers of copper foil are short-connected and the heads and the ends of all even layers of copper foil are short-connected. Because the flexible circuit board has excellent flexibility, which can be bended, curled and twisted on the magnetic core, the integration of inductanceand capacitor is realized and the integral differential mode capacitor value is strengthened by the multilayer parallel flexible circuit board with tube type. The utilization of the invention facilitates to reduce the volume of the EMI electric wave filter and increase the power density of the power electronic transformer.