NOVELTY - A PIN-type polymer solar battery comprises substrate (1), transparent conductive metal oxide anode layer (2), anode modification layer (3), P-type electron donor P layer (4), photoelectric active layer I (5) formed by mixing P-type and N-type electron donor and electron acceptor, N-type electron acceptor layer (6), with or without cathode decorating layer (7) and low work function cathode layer (8).    USE - PIN-type polymer solar battery.    ADVANTAGE - The solar battery has simple preparation, low cost, good repeatability, and is suitable for industrial production.    DETAILED DESCRIPTION - A PIN-type polymer solar battery comprises substrate (1), transparent conductive metal oxide anode layer (2), anode modification layer (3), P-type electron donor P layer (4), photoelectric active layer I (5) formed by mixing P-type and N-type electron donor and electron acceptor, N-type electron acceptor layer (6), with or without cathode decorating layer (7) and low work function cathode layer (8); and one end of transparent conductive metal oxide anode layer deposited with metal wire (9) connected with load or testing device (10), one end of low work function cathode layer connected with load or testing device, and other end. An INDEPENDENT CLAIM is included for a preparation of PIN-type polymer solar battery comprising sputtering metal oxide transparent conductive metal oxide anode layer on substrate of glass or polyester film, preparing anode modification layer as transparent conductive metal oxide anode layer spin coating 3,4-ethylenedioxy thiophene-polystyrene sulfonic acid aqueous solution, with coating thickness of 10-50 nm, baking to obtain anode modification layer as P-type electron donor P layer, dissolving in solvent, spin coating anode modification layer under 1000-6000 revolutions/minute, with mixed solution of P-type electron donor material and electron acceptor material N-type, and passing P-type electron donor material and electron acceptor material N-type through one or two of the crosslinking, with coating film having thickness of 10-500 Angstrom ; processing photoelectric activity I layer in thermal crosslinking or ultraviolet light crosslinking, spin coating directly on P-type electron donor P layer as photo-electric activity I layer at 1000-6000 revolutions/minute; and dissolving N-type electron acceptor material in solvent, with rotating speed of spin coating photo-electric activity I layer at 1000-6000 revolutions/minute, with coating thickness of 1-100 Angstrom , preparing low work function cathode layer on N-type electron acceptor N and vacuum evaporating metal material used as cathode layer.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the PIN-type polymer solar battery.    Substrate (1)    Transparent conductive metal oxide anode layer (2)    Anode modification layer (3)    P-type electron donor P layer (4)    Photoelectric active layer I (5)    N-type electron acceptor layer (6)    Cathode decorating layer (7)    Low work function cathode layer (8)    Metal wire (9)    Testing device (10)