A solid electrolytic condenser with a composite solid electrolyte is composed of an anode made of a valve metal or a valve metal oxide, a valve metal oxide dielectric layer disposed on a surface of the anode, and the composite solid electrolyte disposed on a surface of the dielectric layer; and the composite solid electrolyte at least contains a manganese dioxide first solid electrolyte and a conductive macromolecule second solid electrolyte. The solid electrolytic condenser using the composite solid electrolyte has a high working voltage, a low leakage current and a low equivalent series resistor, and has the advantages of simple process and controllable performance.