Abstract: A series of carbon fiber (CF) / polyether polyurethane (PU) composites were prepared by in situ polymerization and a casting compression molding technique. The influence of CF content and its pretreatment with a coupling agent and oxidation by 65%-68% (mass fraction) nitric acid on the mechanical performance, thermal properties and morphology of the composites was investigated by TGA, SEM and mechanical tests. Results showed that coupling agents improve the mechanical performance of the CF/ PU composites, especially for silane coupling agents KH5501, KH602 and the titanate coupling agent TCA-K44. Nitric acid oxidation also improved the mechanical performance and thermal stability of the composites. The adhesion between PU and nitric acid-oxidized CFs was better than that between PU and fibers treated with silane coupling agents.