Abstract: The disclosure discloses a high-frequency transmission LCP film and preparation method thereof. The preparation method comprises the following steps: (1) separately performing acetylation on monomers to obtain acetylated monomers; (2) performing high-temperature polymerization on the acetylated monomers, phenolic resin, acetic anhydride and zinc acetate, and performing pulverization to obtain liquid crystal copolyester; (3) ball milling the liquid crystal copolyester, an inorganic filler, a silane coupling agent and a glass fiber and mixing to obtain a mixture; and melt-plasticizing the mixture to form a film after cooling, performing longitudinal and transverse synchronous stretching, then winding and slitting the film to obtain a high-frequency transmission LCP film.