Abstract: Carbon fiber/epoxy composites had been widely used in aerospace, rail transit, automobile and other fields because of their high specific strength, specific modulus and good fatigue resistance. However, as one of the main structural forms of carbon fiber/epoxy composites, the laminate structure had the weakest interlayer performance due to the lack of fiber in the thickness direction, which was prone to delamination failure and affects the bearing performance of the structure. Short fiber intercalation toughening was an effective means to improve the interlaminar properties of carbon fiber/epoxy composites. In recent years, scholars at home and abroad had carried out a lot of relevant research work, but there was still a lack of systematic research on short fiber intercalation toughening. In this work, carbon fiber, flax fiber and Kevlar fiber were selected as intercalated short fibers. The effects of short fiber types, intercalation layer density and fiber length on the interlaminar toughening effect of carbon fiber/epoxy composites were systematically analyzed and discussed. The results show that for different short fiber intercalations, the interlaminar fracture toughness of composites increases first and then decreases with the increase of short fiber length and intercalation layer density. On this basis, the toughening mechanisms of different kinds of fibers are revealed. Fiber bridging, change of crack propagation path, multi-layer failure and longitudinal tearing of fibers are helpful to improve the interlaminar fracture toughness of composites. The research results lay a foundation for the structural design of short fiber intercalated toughened composites.