The effects of heat treatment ((300–500 °C) × 30 min) on the interfacial structure, microstructure, and tensile properties of Al4343/Al3003/Cu composites prepared by different accumulative roll bonding (ARB) passes are studied by scanning electron microscopy, energy dispersion spectrometry, electron backscattered diffraction, and tensile tests at room temperature. The results show that the total thickness of the diffusion layer at the Al3003/Cu interface in the same ARB pass Al/Al/Cu composite increases with the increase in temperature. At the same temperature, the total thickness of the diffusion layer at the Al3003/Cu interface increases from ARB0 to ARB3 passes and decreases at ARB5 passes. In the same ARB pass Al/Al/Cu composites, the grains of Al4343 grow with the increase of temperature; the grain of Al3003 increases slightly from 300 to 400 °C, and grows along the interface direction after 500 °C. After 400 and 500 °C, the final average grain size of Cu decreases from ARB0 to ARB3 passes and increases slightly at ARB5 passes. The tensile properties of the composites are affected by recovery and recrystallization at lower temperatures and ARB passes, and by the total thickness and volume fraction of the diffusion layer at higher temperatures and ARB passes.