NOVELTY - Low-fluorine solar battery protective film prepared by extrusion casting or film blowing of fluorine containing thin film comprising 40-55 pts. wt. fluoro resin, 0.5-4.5 wt.% silane coupling agent, 0.01-0.6 wt.% organic peroxide, 0.01-0.8 wt.% cross-linking catalyst, 10-45 pts. wt. inorganic filler, 10-40 pts. wt. modified resin, 0.01-1.0 pts. wt. lubricant, and 0-2 pts. wt. functional auxiliary agent is claimed. The fluororesin is ethylene-chlorotrifluoroethylene copolymer. The inorganic filler is oxide of titanium, aluminum, tin or silicon elements.    USE - The method is useful for preparing low-fluorine solar battery protective film (claimed).    ADVANTAGE - The method: produces low-fluorine solar battery protective film, which has excellent anti-ultraviolet aging characteristics, and moisture and weather resistance; improves mechanical property of the film; and has low cost.    DETAILED DESCRIPTION - Low-fluorine solar battery protective film prepared by extrusion casting or film blowing of fluorine containing thin film comprising 40-55 pts. wt. fluoro resin, 0.5-4.5 wt.% silane coupling agent, 0.01-0.6 wt.% organic peroxide, 0.01-0.8 wt.% cross-linking catalyst, 10-45 pts. wt. inorganic filler, 10-40 pts. wt. modified resin, 0.01-1.0 pts. wt. lubricant, and 0-2 pts. wt. functional auxiliary agent is claimed. The fluororesin is ethylene-chlorotrifluoroethylene copolymer. The inorganic filler is oxide of titanium, aluminum, tin or silicon elements. The modified resin is polymethyl methacrylate or polyethyl methacrylate. The function auxiliary agent is antioxidant, anti-aging agent, light stabilizer and/or light absorbent. The silane coupling agent is vinyltrimethoxysilane or vinyl triethoxysilane. The organic peroxide is dicumyl peroxide or dibenzoyl peroxide. The crosslinking catalyst is di-butyltin dilaurate, dibutyl tin laurate maleate, di-n-octyl dilaurate, dodecylbenzene sulfonic acid, acetyl dodecylbenzene sulfonate, toluenesulfonic acid and/or acetyl toluene sulfonate. An INDEPENDENT CLAIM is also included for preparing the low-fluorine solar battery protective film comprising step (i) dividing fluoro resin into two parts respectively, extruding the first part with silane coupling agent and organic peroxide to prepare master batch A, extruding the second part and the cross-linking catalyst to prepare master batch B, where the mass ratio of fluoro resin in the master batch A and master batch B is 90-98:2-10, and step (ii) mixing master batch A and master batch B with the inorganic filler, modified resin, lubricant and functional auxiliary agent by extrusion casting or blowing to obtain fluorine-containing thin film, and crosslinking at 85 plus minus 5 degrees C for 9-10 hours on a water bath.