NOVELTY - A polyester coating polyester thin film contains thin film of polyethylene terephthalate or poly 2,6-polyethyelene naphthalate (PEN) biaxially oriented polyester thin film and polyester glue coated on 2 side surface of the film coating in which thickness of polyester thin film is 150-250 mu m and thickness of polyester glue coating is 0.08-0.25 mu m.    USE - Polyester coating polyester thin film for manufacture of thin film solar battery back film or polyester thin film product.    ADVANTAGE - Product has low water vapor transmission rate , good film-forming property and appearance, excellent adhesion and barrier property, stable property, and improved service life and working efficiency.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of polyester coating polyester thin film which involves weighing 40 pts. wt. deionized water to container, stirring 16-50 pts. wt. polyester resin containing-25% water-soluble polyester emission, continuously stirring for 30 minutes, controlling pH value to 9.5 by dripping pH adjusting agent N,N-dimethylethanolamine, adding 1.2-3.75 pts. wt. nano silica sol, 0.5-1 pt. wt. surfactant, 0.2-0.5 pt. wt. flatting agent, and 0.2-0.5 pt. wt. defoaming agent, adding 0.12-0.625 pt. wt. curing agent, adding deionized water to obtain 100 pts. wt. total material, controlling pH value to 9.5 by adding N,N-dimethylethanolamine, stirring for 30 minutes to obtain polyester glue, drying polyester slice to extruder at 265-300 degrees C, extruding die lip, subjecting to 12-20 degrees C cold drum, entering at speed of 10-20 m/minute and length of 3-5 m, performing lengthwise stretching at 65-95 degrees C and folding for 3 plus minus 0.8 times, subjecting to cooling corona section at 22-76 m/minute, cooling to 15-45 degrees C for 1-3 s, performing corona treatment, subjecting stretched polyester film to corona treatment and online coating device, coating polyester glue by roller, coating polyester thin film on 2 sides at thickness of 0.08-0.25 mu m, performing lengthwise stretching, performing corona treatment of polyester film and subjecting to 5-9 m length, preheating to 100-135oC to remove water, subjecting to 8-12 m length, performing transverse stretching to 135-155 degrees C and folding for 3.0 plus minus 0.8, subjecting to 10-16 m length, subjecting to hot setting section to 225-245 degrees C for 0.1 to 0.8 minute, cross-linking and curing forming compact coating at 60-80 degrees C, subjecting to room temperature for 0.1-1 minute, cooling by 2 stages of room temperature rolling, in which nano silica sol is nano silica emission, surfactant is modified dimethylsiloxane, flatting agent is polyether siloxane, defoaming agent is organic silicon polyether copolymer, curing agent is butyl ether amino resin or isocyanate, and polyester slice is polyethylene glycol terephthalate slice or poly 2,6-polyethylene naphthalate (PEN).