Abstract: Based on the free volume theory and the experimental results,the contributions of the components to T_g of the network were analysed.To determine the effect of curing agent,the fracture toughness of epoxy network,cured by DDS was investigated.The experimental results showed that K_Ic of epoxy network cured by DDS was much tougher than the corresponding network cured by BF₃MEA.According to the above analysis,the network of matrix was deliberately designed,in order to improve the interlaminar toughness of composite without the degradation of its high temperature performance,and the feasibility of this method was confirmed by the experimental data.