In this study, E51 was appended as an additive to the PES casting solution and hybrid PES/E51 films with different E51 content were produced by phase inversion approach, applied as interleaves to improve the interlaminar fracture toughness of CF/EP composite laminates prepared by vacuum assistant resin infusion process (VARI). The time that the hybrid film dissloved into the epoxy resin depended on the content of E51 in the film, moreover, it was observed that Mode I fracture toughness of the hybrid film modified composite reduced with the addition of E51 compared with the pure PES film interleaved composite, however, the tensile properties showed the opposite tendency. The reason was the reduction in the thickness of the interlayer resin illustrated by cross-section morphologies of all types of laminates.