According to the rheological properties, gel time, etc., the basic formula of prepreg resin was obtained.The optimum synthesis process of prepreg resin was obtained, taking the surface quality of cured resin as evaluation standard. It can reduce the energy consumption and solve the problem of uneven dispersion of dicyandiamide. The experimental results show that the optimum amount of gas phase nano SiO₂ is 1% as toughening agent, the tensile and impact strength of the cured resin are 74.41 MPa and 20.23 kJ/m² respectively, which are increased by 72.64% and 58.79% compared with those before toughening. Finally, the prepreg resin formula is determined as the mass ratio of E-51, E-20, NPCN704, dicyandiamide, dichlorophenyl dimethyl urea, gas phase nano SiO₂, defoaming agent of 50:30:20:7:2:1:0.2, and the curing process is determined as 100 ℃/1 h+130 ℃/2 h+150 ℃/2 h according to the extrapolation of DSC non-isothermal curve. The mechanical properties of the casting and composites were compared with commercial prepreg resin, and the results show that the self- made prepreg resin is excellent. Glass fiber and carbon fiber reinforced self-made prepreg resin composites were prepared by vacuum assisted molding process, and the resin content should be controlled at 40% and 35%, respectively.