The invention discloses a compound type LCP (Liquid-
Crystal Polymer) high-frequency high-speed double-sided 
copper foil substrate. The compound type LCP high-frequency high-speed double-sided 
copper foil substrate comprises one or more LCP core layer, one or more extremely-low 
dielectric adhesive layer and two 
copper foil 
layers, the LCP core layer and the extremely-low 
dielectric adhesive layer are arranged between the two 
copper foil layers, wherein the thickness of the each LCP core layer is 5 to 50 micronmeters; the thickness of the each extremely-low 
dielectric adhesive layer is 2 to 50 micrometers; the thickness of the each 
copper foil layer is 1 to 35 micrometers, the extremely-low dielectric adhesive 
layers are adhesive layers of which Dk values are 2.0 to 3.0 (10GHz) and Df valuesare 0.002 to 0.010 (10GHz). The compound type LCP high-frequency high-speed double-sided 
copper foil substrate disclosed by the invention has the advantages of good 
electricity, low roughness, stabledk / df performance under a high-temperature 
moisture environment, ultra-low water 
absorption rate, good 
UV laser drilling ability, low rebounding force for high-density 
assembly and excellent mechanical performance; in addition, based on a current 
coating technology, the 
coating thickness of about 50 micrometers at most only can be required. According to the preparation method disclosed by the invention, the substrate, of which the thickness is 100 micrometers or above, can be easily obtained.