NOVELTY - A solar cell back board compounded to a film by 3 polymer film layers by a multi-layer fusion coextrusion method, comprises bonding weather-proof layer, bonding enhanced layer and bonding moisture barrier layer from top to bottom. The bonding weather-proof layer takes polyvinylidene fluoride resin and ethylene-vinyl acetate copolymer resin as main materials, and mixed assistant comprising inorganic white pigment, UV resistant stabilizer, anti-thermal oxidative aging stabilizer and crosslinker is added such that a blending plastic alloy layer is formed.    USE - A solar cell back board.    ADVANTAGE - The board only has 3 layers of structures, and does not employ an adhesive layer. Its preparation process is simple, saving the steps of gluing and thermally pressing, and is high in production efficiency. The back board is excellent, meeting the packaging requirement of the solar cell.    DETAILED DESCRIPTION - Solar cell back board compounded to a film by 3 polymer film layers by a multi-layer fusion coextrusion method, comprises bonding weather-proof layer, bonding enhanced layer and bonding moisture barrier layer from top to bottom. The bonding weather-proof layer takes polyvinylidene fluoride (PVDF) resin and ethylene-vinyl acetate copolymer (EVA) resin as main materials, and mixed assistant (I) comprising inorganic white pigment, UV resistant stabilizer, anti-thermal oxidative aging stabilizer and crosslinker is added such that a blending plastic alloy layer is formed. The PVDF resin and EVA resin are 60 wt.% and a weight ratio of PVDF resin to EVA resin is 50-90:50-10. The bonding enhanced layer takes polyethylene glycol terephthalate (PET) resin and polymethylmethacrylate (PMMA) resin as main materials, and mixed assistant (II) comprising inorganic white pigment, UV resistant stabilizer and anti-thermal oxidative aging stabilizer is added such that a blending plastic alloy layer is formed. The PET resin and PMMA resin are 70 wt.% and a weight ratio of the PET resin to the PMMA resin is 60-90:40-10. The bonding moisture barrier layer takes PVDF resin and polyvinyl butyral (PVB) resin as main materials, and mixed assistant (III) containing inorganic white pigment, UV resistant stabilizer and anti-thermal oxidative aging stabilizer is added such that a blending plastic alloy layer is formed. The PVDF resin and PVB resin are 60 wt.% and a weight ratio of the PVDF resin to the PVB resin is 50-90:50-10.