The invention discloses a method for preparing a high-temperature superconducting 
coating conductor La0.7Sr0.3MnO3 buffering layer film, and belongs to the technical field of high-temperature superconducting 
materials preparation. The film prepared by the method is smooth and compact, and is favorable in texture, and triplex functions of La0.7Sr0.3MnO3 as a conducting buffering layer film, namely isolation, extension and 
electric current transmission, can be adequately exerted. The method comprises the following steps: dissolving analytically pure 
lanthanum oxide (La2O3) in 
acetic acid (the mol ratio of the 
acetic acid to cations being 10: 1) in a cation ratio of La: Sr: Mn=0.7: 0.3: 1; after the analytically pure 
lanthanum oxide is completely dissolved, putting the obtained solution in an 
infrared drying box, and after the solution is baked into a white 
solid, taking out the white 
solid; mixing and dissolving 
strontium acetate and 
manganese acetate with the prepared white 
solid (namely 
lanthanum acetate) in propionic acid in the cation ratio of La: Sr: Mn=0.7: 0.3: 1 to form an 
anhydrous solution; adding 
polyvinyl butyral (PVB) in the 
anhydrous solution to prepare into a 
colloid with good film forming property; and 
coating the 
colloid on a substrate, 
drying the coated substrate, and then, putting the dried substrate in a 
sintering furnace to be sintered to form a phase, so as to obtain a lanthanum-
strontium-
manganese oxide La0.7Sr0.3MnO3 high-temperature superconducting 
coating conductor buffering layer. The cost of the method is low; the manufacturing process is simple; the operation is easy to control; and the environment is not polluted.