The invention relates to a flexible transparent medlin membrane material and a relative preparation method, wherein the invention polymerizes 4, 4'-bis(3', 4'-dicarboxyphenoxy), 2, 2'-bis(trifluoromethyl)-4, 4'-benzidine, 3, 3'-diaminodiphenylsulfone dapsone and 3, 3'-dimethyl-4, 4'-diamino diphenyl methane in polar solvent to obtain medlin, uses tape casting method to treat the medlin on a clean glass plate, bakes in a membrane bake oven at 80DEG C for 2h until the solvent is volatilize and the membrane is solidified, moves the glass plate coated with a medlin membrane into an oven, increases the oven temperature from room temperature to 350DEG C at the heating rate of 2DEG C/min, naturally cools to room temperature, takes out the glass plate coated with one medlin membrane from the oven, arranges the glass plate into water, boils water to remove the medlin membrane from the glass plate, to obtain flexible transparent medlin membrane material. The ultraviolet cut-off wavelength of the medlin membrane is 395-430nm, and the glassivation transformation temperature is 254-280DEG C.