NOVELTY - An organic film solar battery comprises a substrate, an anode layer, a cathode layer, and an organic function layer arranged between the anode layer and the cathode layer; where the organic function layer comprises an electron donor layer and an electron acceptance layer; the electron donor layer and electron acceptance layer are increased in area by using magnetic multi-wall carbon nano tube and magnetic single-wall nano tube; and the electron donor layer comprises an electron donor material and a magnetic multi-wall carbon nano tube or magnetic multi-wall nano tubes with different lengths.    USE - The organic film solar battery is useful for industrial and commercial applications.    ADVANTAGE - In the organic film solar battery, the magnetic multi-wall carbon nano tube and the magnetic single-wall nano tube have high visible light transmittance and low resistance; where the amount of baryons can be increased in apparatus, and the electron and the hollow cavity in the interface can be transmitted to the electrode layer; thus, the energy conversion efficiency of the organic film solar battery can be improved.    DETAILED DESCRIPTION - An organic film solar battery comprises a substrate, an anode layer, a cathode layer, and an organic function layer arranged between the anode layer and the cathode layer; where the organic function layer at least comprises an electron donor layer and an electron acceptance layer; the electron donor layer and the electron acceptance layer are increased in area by using magnetic multi-wall carbon nano tube and magnetic single-wall nano tube; the electron donor layer comprises an electron donor material and a magnetic multi-wall carbon nano tube or magnetic multi-wall nano tubes with different lengths; the electron acceptance layer comprises an electron acceptance material; the electron donor layer comprises an electron acceptance material; the electron acceptance layer comprises an electron donor material and a magnetic single-wall carbon nano tube or magnetic single-wall nano tubes with different lengths; the length directions of the multi-wall nano tubes and the single-wall carbon nano tubes are vertical to the anode layer surface; and the lengths of the multi-wall nano tubes and the single-wall carbon nano tubes are more than the thickness of the electron donor material or the electron acceptance material and less than its total thickness. An INDEPENDENT CLAIM is a preparation method of the organic film solar battery, comprising: (a) cleaning the substrate, and drying it; (b) placing the substrate into the evaporation chamber to prepare the anode layer; (c) using vacuum plating or coating to prepare the organic function layer; where the organic function layer at least comprises an electron donor layer and an electron acceptance layer; (d) keeping vacuum pressure and preparing the cathode in the vacuum chamber after the organic function layer is prepared; and (e) transmitting the prepared apparatus to the sleeve case to be packed; where the sleeve case is filled with nitride.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the organic film solar battery.