PURPOSE: To eliminate anisotropy from properties of film when liquid crystal polyester is melt-extruded to mold the film by a method wherein the melt-extrusion temperature is kept between the transition temperature of the liquid crystal phase of said polyester and that of the isotropic phase thereof or higher.

CONSTITUTION: When liquid crystal polyester is melt-extruded to mold the film, the transition temperature of the liquid crystal phase of said polyester to the isotropic phase thereof or higher is used as the melt-extrusion temperature of the liquid crystal of the polyester. Film prepared in such a method is extruded from an orifice and continues to be cooled, polymer chains are oriented almost isotropically and densely within the film surface to obtain the film of high strength, high Young's modulus, almost free from anisotropy in mechanical properties, thermal properties, etc.