The heating treatment technical parameters and the microstructure of diffusion layer was investigated after cold-rolling bonding for the Cu/Al composite strips by a tensile testing machine, metalloscope, XRD, EMPA, etc. Results show that with the increasing of the annealing temperature or prolonging of the holding time, the Cu/Al composite strips have a lower strength and higher plasticity, and the interface width of composite strips is from 1.5 μm to 6.5 μm. In a conclusion, 410 oC/10 min is the best heating treatment parameter. There are five intermediate phases, Cu9Al4, Cu4Al3, Cu3Al2, CuAl, and CuAl2. The size of these intermediate phases is relatively small and at the quality grade of 10-4~10-8mm2. The morphology of Cu9Al4, Cu4Al3 and Cu3Al2 is polygonal lump. Also there are a lot of parallel laths in the Cu9Al4. The form of CuAl2 phase is similar to ovoid and that of CuAl phase is dispersive grain