The microstructures of Cu75.15Al24.85 alloy before and after treatment at 15 GPa pressure and 750℃ for 15 min are analyzed by optical metallograph, X-ray diffraction, scanning electron microscopy and differential scanning calorimeter, and its resistivity is also obtained through resistivity measuring instrument. According to the obtained results, the effects of high pressure treatment on the microstructure and resistivity are investigated. The results show that high pressure treatment can refine the microstructure, and increase the resistivity of the alloy. When the pressure is 3 GPa, the refinement is more remarkable and the resistivity reaches a maximal value.