The toughened composite was prepared by the domestic high strength medium modulus carbon fiber (CCF800H) reinforced epoxy resin matrix. The influence of different content of toughening thermoplastic within epoxies on the mode-Ⅰ interlaminar fracture toughness (G_ⅠC) of composites was investigated. The results show the initial strain energy release rate (G_ⅠC-init) and the propagational strain energy release rate (G_ⅠC-prop) of composites improve remarkably with the increasing of content of toughening thermoplastics within epoxy matrix. In the case of mass fraction of thermoplastic is greater than 20% of epoxy, the toughening aromatic polyetherimide particle can be concentrated on the interlayer of composite to form the high interlaminar toughness zone. The interlaminar toughened structure constituted by ‘continuous phase’ and ‘dispersion phase’ is fabricated on the interlayer of composite.