A dual-channel parallel type organic-inorganic composite solar cell based on a primary crystalline porous nanometer germanium film takes the primary crystalline porous nanometer germanium film having an n type conductive characteristic as a base. An organic donor/organic acceptor active layer is formed on the primary crystalline porous nanometer germanium film through a spin coating method. The organic donor/organic acceptor forms a plane heterojunction while the organic donor/organic acceptor forms a bulk heterojunction. In a composite structure where the bulk heterojunction and the plane heterojunction coexist, the parallel mode of the dual-channel transportation of carriers can be realized. Furthermore the solar spectrum absorption of the cell is enhanced and expanded while the cell transportation performance is improved. The primary crystalline porous nanometer germanium film having the n type conductive characteristic is prepared by coupling a plate capacitor with a plasma enhanced chemical vapor deposition (PECVD) system at the room temperature. The dual-channel parallel type organic-inorganic composite solar cell based on the primary crystalline porous nanometer germanium film has the advantages that the parallel dual-channel transportation mode of the carriers is combined with the characteristics of the narrow band gap, the high absorption coefficient, the high carrier mobility of a germanium material, and the organic cell carrier transportation capacity and the solar spectrum absorption are together prompted.