Abstract: The influence of composition on the curing kinetic parameter, electrical, mechanical, thermal properties and the glass transition temperature (T_g) of epoxy and cyanate ester co-curing system catalyzed by transition metal acetylacetone(M_T(atat)_<em>n) was studied by means of DSC,dielectric and dynamic mechanical methods in this paper. The results showed that the reactive activation energy (E_a) and frequency factor (A) of the co-curing is found to increase with enhanced concentrations of cyanate of the co-curing system. The glass transition temperature (T_g) and thermal stability of the cyanate and epoxy cured system is found to increase with enhanced concentrations of cyanate in the same cured condition; addition of the cyanate will decrease the loss factor, and dielectrical value as well.