Diffusion bonding of pure aluminum to pure nickel by organic solvent surface protection has been investigated at various temperatures. The interfacial microstructure of Al/Ni diffusion bonded joint was confirmed to be Al/Al3Ni2/Ni by scanning electron microscope, energy spectrum analysis and X-ray diffraction (XRD) analysis method. The organic solvent was used to protect the "clean surface" against re-oxidation prior to diffusion bonding. Under optimum conditions, the joints with higher shear strength were obtained. As the temperature increased, the thickness of the reaction layers increased gradually. The highest shear strength obtained by organic solvent surface protection bonding was17.83MPa under a pressure of 2MPa for 60 min at temperatures of 490°C, which was 55% higher than those obtained by conventional diffusion bonding.