Abstract: As main aviation materials, there are a lot of assembly relationships between carbon fiber/epoxy composites and aluminum in aircraft structures. However, due to limitation of the composite forming process, assembly gaps will be created between the mating surfaces in the case of manufacturing and assembly deviations. When the gap exceeds a certain size, gap-filling compensation is necessary. Based on the actual structure, the carbon fiber/epoxy composite-aluminum assembly model was abstracted, the assembly test bench was used to simulate the pre-tightening force of the bolt, and the strain gauge and 3D digital image correlation(3D-DIC) experiment were used to compare the strain on the surface under the condition of forced assembly and gap-filling compensation in older to analyze the deformation rule of the component. The interlaminar stress analysis was carried out by finite element method, and the effects of gap-filling compensation on the interlaminar stress and local damage of the carbon fiber/epoxy composite-aluminum assembly structure were studied by extracting the stress components and damage of the cohesive element. The results of experimental and simulation analysis show that with the assembly gap increasing, the strain values increase; Gap-filling compensation improves the strain state caused by the bending deformation, while the strain of the bolt head extrusion zone is also increased. In general, gap-filling compensation makes the strain distribution more uniform and reduces damage of the carbon fiber/epoxy composite, and the liquid shim effect is slightly better than the peelable shim.