Rising oil price and pressure to reduce emission push aerospace Original Equipment Manufacturers (OEMs) to use more and more polymer matrix composites (PMC) to reduce weight. Secondly, OEMs also try their best to reduce cost. They keep their eyes on improving repair and maintenance of PMC. Thermoplastics possess excellent comprehensive performance. First of all, OEMs prefer their high toughness, unique processing through heating and cooling, excellent fire smoke and toxicity properties with indefinite shelf life. High performance thermoplastic resin containing phthalazinone moieties are a new important family of high-performance polymers possessing an outstanding balance of mechanical properties and processability along with excellent thermooxidative stability. Poly(phthalazinone ether)s are a kind of potential thermoplastic matrix for polymer matrix composites. They present excellent mechanical properties, especially at elevated temperature. We also developed a novel approach to introduce amino group (-NH2), hydroxyl group (-OH) and sulfhydryl group (-SH) onto carbon fibers (CFs) using aromatic diazonium salts chemically and uniformly to improve their interfacial properties. Fourier transform infrared spectroscopy (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and single fiber tensile testing were performed to characterize the functional CFs. Interlaminar shear strength (ILSS) and flexural strength were carried out to investigate the interfacial properties of CFs/PPBES composites. Experimental results showed that -NH2, -OH and -SH were grafted on the CFs surface uniformly and increase the fibers surface roughness significantly. The functionalization did not lead to any discernable decrease in the fibers tensile strength (TS). ILSS and flexural strength were enhanced obviously. Additionally, the reinforcing mechanisms were also analyzed.