Abstract: The experiment of using modifier B to improve the dissolvability of the prepolymer of bismaleimide/diamine is reported. The prepolymer can be dissolved in acetone easily and the solution has enough long harmonious stage at room temperature. It makes convenient for preparing prepreg.Meanwhile, the properties of resins have been studied by DSC and TG analysis method and the composite's performance is characterized by interlaminar shear strength(ILSS) at room temperature, 150℃ and 200℃.