The invention relates to an 
epoxy resin composition and a high-frequency circuit board manufactured thereby. The 
epoxy resin composition comprises the following 
solid components: (A) 
cyanate compound or 
prepolymer thereof, wherein the molecule of the 
cyanate compound contains at least two cyanato groups; (B) active ester; and (C) 
epoxy resin containing a naphthol structure; calculated in 
solid component in parts by weight, the total amount of the component (A), i.e. the 
cyanate compound containing at least two cyanato groups in the molecule thereof or the 
prepolymer thereof, and the component (B), i.e. active ester, is 10-70 parts by weight, and the amount of the component (C), i.e. epoxy resin containing naphthol structure, is 30-90 parts by weight, wherein the weight ratio of the component (A), i.e. the 
cyanate compound containing at least two cyanato groups in the molecule thereof or the 
prepolymer thereof, to the component (B), i.e. active ester, is (0.2-5):1. The high-frequency circuit board manufactured by using the epoxy resin composition of the invention comprises a plurality of 
layers of prepregs which are overlapped mutually, and 
copper foils which are compressed on the two sides respectively; and each of the plurality of 
layers of prepregs comprises a base material and the epoxy resin composition which is adhered to the base material through impregnation and 
drying.