The invention relates to a liquid crystal polymer composition and a preparation method thereof. The liquid crystal polymer composition is prepared from the following raw materials: liquid crystal polymer A resin, liquid crystal polymer B resin, hydrogenated styrene-butadiene-styrene copolymer grafted maleic anhydride, hollow glass beads, a polyhedral oligomeric silsesquioxane polymer, low-dielectric-constant glass fibers, a titanate coupling agent, polytetrafluoroethylene resin, a hyperbranched polyester polymer, erucyl amide, an antioxidant CY, and bis(2,4-dicumyl phenyl) pentaerythritol diphosphite. The liquid crystal polymer composition has excellent mechanical properties, processability, thermal properties and low dielectric constant, and can be applied to shells, cladding and protective materials and the like of 5G base stations, micro base station systems, data communication terminals, antennas and radio frequency modules.