Abstract: A type of CF bundle wound with PBO(Poly-p-phenylene benzobisoxazole) filament was designed, and than the epoxy composites with the CF bundles were prepared by vacuum assisted resin transfer molding (VARTM). The flexural strength and modulus of the PBO-CF/epoxy composites were evaluated by a three-point bending test method, the bending failure modes were observed by a scanning electron microscope. The influence of filament winding methods on the failure process was studied. The result indicated that filament winding could effectively improve the flexural strength of epoxy/CF composites. The composites achieved an increase in flexural strength by 20 % through the unidirectional rotation-winding method and an increase by 36 % through the bi-directional rotation-winding mode. The damages of three point bending were all observed on the compression surface. The failure process of filament-winding carbon fiber-reinforced composites was resulted by the compressive yield of a single bundle rather than by a single fiber. Moreover the interfacial adhesion between the PBO-CF and epoxy matrix was poor, thus resulting in a limitation for the further improvement of flexural properties.