High-performance polyurethane materials are attracting more and more attention. In this work, a cooperativeimprovement of strength and toughness of rigid polyurethane (RPU) composites was achieved. 1.0 wt% long carbon fibers(LCFs) reinforced RPU composites were prepared and the effects of fiber oxidation treatment were studied. The resultsindicated that the surface roughness and wettability of LCFs were both increased, which could provide better physicalbonding between LCFs and RPU matrix. Moreover, the increasing -OH groups on the fiber surface would react with RPU toform chemical bond. With the strengthened physical and chemical bonds, the interface of LCFs/RPU composites has beeneffectively improved. The mechanical properties showed that compared with pure RPU, the tensile strength, tensile modulus,bending strength, bending modulus, and impact strength of oxidized LCFs/RPU composites were increased by 171.1 %,814.3 %, 29.1 %, 125.8 % and 110.1 %, respectively. Interlaminar shear strength (ILSS) was also increased by 65.1 %. Dynamic thermomechanical analysis (DMA) and scanning electron microscope (SEM) indicated the positive effects of theoxidation treatment on the interfacial bonding between LCFs and RPU matrix.