Because of the challenge of compounding lightweight, high-strength Ti/Al alloys due to their considerable disparity in properties, Al 6063 as intermediate layer was proposed to fabricate TC4/Al 6063/Al 7075 three-layer composite plate by explosive welding. The microscopic properties of each bonding interface were elucidated through field emission scanning electron microscope and electron backscattered diffraction (EBSD). A methodology combining finite element method-smoothed particle hydrodynamics (FEM-SPH) and molecular dynamics (MD) was proposed for the analysis of the forming and evolution characteristics of explosive welding interfaces at multi-scale. The results demonstrate that the bonding interface morphologies of TC4/Al 6063 and Al 6063/Al 7075 exhibit a flat and wavy configuration, without discernible defects or cracks. The phenomenon of grain refinement is observed in the vicinity of the two bonding interfaces. Furthermore, the degree of plastic deformation of TC4 and Al 7075 is more pronounced than that of Al 6063 in the intermediate layer. The interface morphology characteristics obtained by FEM-SPH simulation exhibit a high degree of similarity to the experimental results. MD simulations reveal that the diffusion of interfacial elements predominantly occurs during the unloading phase, and the simulated thickness of interfacial diffusion aligns well with experimental outcomes. The introduction of intermediate layer in the explosive welding process can effectively produce high-quality titanium/aluminum alloy composite plates. Furthermore, this approach offers a multi-scale simulation strategy for the study of explosive welding bonding interfaces.