Since Cu-Al powder characteristics have important effects on the preparation of Cu/Al2O3 composite, the apparent activation energy of Al internal oxidation reac- tion in Cu-Al pre-alloyed powders with different characteristics was calculated in the present investigation. The microstructure and properties of the synthesized Cu/Al2O3 were studied. The results show that high-energy milling can obviously promote in- ternal oxidation of Al in Cu-Al powders in the same solid solubility. At the same milling conditions and internal oxidation parameters, the solid solution of Al in Cu either in low or high amount will result in the poor microstructure and properties of the Cu/Al2O3 composite. Subsequently, when high-energy milling and internal oxidation are synchronously used to prepare the Cu/Al2O3 composite, there should be an appropriate solubility and milling effect for the pre-alloyed powders. Since Cu-Al powder characteristics have important effects on the preparation of Cu / Al2O3 composite, the apparent activation energy of Al internal oxidation reac tion in Cu-Al pre-alloyed powders with different characteristics was calculated in the present investigation. The microstructure and properties of the synthesized Cu / Al2O3 were studied. The results show that high-energy milling can significantly promote in- ternal oxidation of Al in Cu-Al powders in the same solid solubility. At the same milling conditions and internal oxidation parameters, the solid solution of Al in Cu either in low or high amount will result in the poor microstructure and properties of the Cu / Al2O3 composite. There should there be an appropriate solubility and milling effect for the pre-alloyed powders.