Abstract: The weak interface strength between carbon fiber (CF) and polymer matrix severely limits their practical application in fields such as automotive lightweighting. To address this issue, a series of boehmite/graphene with different content were prepared by hydrothermal method and successfully introduced to the surface of CF via self-assembly method to modify the interface of carbon fiber/epoxy resin composites (CF/EPs). A series of tests were conducted to investigate the mechanical properties of the composites before and after modification and the results showed that the best performance was achieved when the boehmite/graphene mass ratio was 1∶2 (BG-2). Compared with CF/EP, the modified BGCF/EP-2 showed significant enhancements in IFSS (116.1%), ILSS (56.0%), tensile strength (61.1%), and flexural strength (30.4%). Finally, the schematic diagrams of the possible multiscale interfacial modification mechanism in the CF/EPs were further analyzed based on the results of SEM images and contact angle tests.