The macro-properties of CF/PPEK and CF/PPES, which are two kinds of high performance thermoplastic composites, depend greatly on their interfacial structures. In this paper interfacial morphological structures of the two composites were investigated and analyzed by X-ray photoelectron spectroscopy (XPS). The results revealed that some new functional groups Were generated that promoted strong physical and chemical interactions on the interface between fiber and matrix of CF/PPEK and CF/PPES composites. High temperature bending properties were tested and analyzed. and the changes in high temperature mechanical properties and retention rates Were followed. A T-r-n model was used to predicted the high temperature mechanical properties of CF/PPEK and CF/PPES composites. The results were consistent with the test results. Which verified the feasibility of the T-r-n model.