An in-depth survey of the researches is presented on the anisotropic structure and properties of inter-phase in carbon fiber reinforced polyetheretherketone composites. The formation and structural nature of interfacial short-range and long-range effects, micromechanical and macromechariical roles of interphase are discussed. Besides, prospects of further studies and a novel methodology for revealing interfacial properties of thermoplastic composites are demonstrated. An in-depth survey of the researches is presented on the anisotropic structure and properties of inter-phase in carbon fiber reinforced polyetheretherketone composites. The formation and structural nature of interfacial short-range and long-range effects, micromechanical and macromechariical roles of interphase are discussed. Besides, prospects of further studies and a novel methodology for revealing interfacial properties of thermoplastic composites are demonstrated.