NOVELTY - An acrylic-coated polyester thin film comprises polyethylene terephthalate or polyethylene-2, 6-naphthalate which is made into biaxially oriented polyester thin film, and acrylic adhesive coating on two sides of polyester thin film. The polyester film has thickness of 150-250 mu m. The acrylic adhesive coating has thickness of 0.08-0.32 mu m.    USE - Acrylic-coated polyester thin film used in manufacturing solar battery back panel membrane.    ADVANTAGE - The polyester thin film has low water vapor transmission rate.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the polyester thin film, comprising:    (A) preparing acrylic adhesive by adding 50 pts. wt. deionized water and 10-40 pts. wt. acrylic resin containing 40% water-soluble acrylic liquid with stirring, continuously stirring for 30 minutes, then dripping pH adjusting agent N,N-dimethylethanolamine to adjust pH value to 9.5, then adding 1.6-6.4 pts. wt. nano silica sol, 0.5-1 pts. wt. surface active agent, 0.2-0.5 pts. wt. leveling agent, 0.2-0.5 pts. wt. defoaming agent, 0.02-0.4 pts. wt. curing agent, then adding deionized water to make total material reach 100 pts. wt., then adding N,N-dimethylethanolamine to adjust pH value to 9.5, and stirring for 30 minutes to obtain acrylic adhesive, where the nano silica sol is silicon dioxide nano liquid, the surface active agent is nonionic polyoxyethylene ether, the leveling agent is isopropanol, the defoaming agent is organosilicon polyether copolymer, and the curing agent comprises melamine-formaldehyde resin and isocyanate;    (B) putting dry polyester slice into an extruder and melting at 265-300 degrees C, entering melt into cold drum and into lengthwise stretching section at 65-95 degrees C, and entering lengthwise stretched polyester thin film into a cooling corona section and cooling for 1-5 seconds at 15-45 degrees C; and    (C) after corona treatment, entering the polyester film into online coating device, coating the polyester film two surfaces with acrylic adhesive coating, then preheating coated film to 100-135 degrees C to remove water, continuously heating to 140-160 degrees C, shaping at 225-250 degrees C, curing the coating at 60-80 degrees C for 0.1-1 minute, and cooling to low room temperature.