The invention discloses an implementation method of an embedded capacitor and a circuit board in the field of manufacturing of circuit boards. A conductive film layer for being used as an electrode of the embedded capacitor is arranged on at least one surface of a conductive pattern layer, a first insulation layer is formed on the conductive film layer, and the first insulation layer contains a window body exposed outside the conductive film layer; a capacitance paste is filled into the window body; pre-curing operation is performed on the capacitance paste; a first conductive layer is pressed on the capacitance paste; graphicalization operation is performed on the first conductive layer for being used as the other electrode of the embedded capacitor. According to the implementation method disclosed by the invention, the closing bonding between the first insulation layer and the conductive pattern layer can be ensured; the contact surfaces between the capacitance paste and the first conductive layer are smooth, gaps which may exist between the capacitance paste and the first insulation layer are filled, and the first insulation layer and the capacitance paste can be also cured, so that high rigidity, small heat expansion coefficient and effect of low probability of cracking of the finally obtained circuit board are further ensured.