In order to improve the quality of explosive welding of 5083Al and 304 stainless steel and improve the thermal insulation effect, in this paper, 1060Al, TA1, and Ni were used as interlayer materials to prepare a five-layer explosive composite plate with thermal conductivity gradient. In order to eliminate the residual stress after explosive welding and reduce defects such as adiabatic shear bands and micro-cracks, the five-layer explosive composite plate was annealed by 550℃/60min, and analyzed by means of SEM, EBSD, and the universal testing machine. The effect of annealing on its microstructure evolution and mechanical properties was studied. The results showed that the four welding interfaces of the five-layer explosive composite plate were all corrugated, and there were defects such as micro-cracks, holes, adiabatic shear bands, and vortex areas at the interfaces. After annealing, the four welding interfaces were recrystallized to different degrees, and the defects such as microcracks and adiabatic shear bands were effectively improved; On the basis of the original TiNi3 melting layer, the interface added a new TiNi melting layer and a new Ti2Ni melting layer. The tensile and shear strengths of the interface had decreased, but they were still far higher than the requirements of the corresponding national standards; the pull-off samples were fractured and separated at the 5083Al/1060Al interface.