Abstract: 50%Si_P/Al-Cu and 70%Si_P/Al-Cu composites were prepared by hot isostatic pressing(HIP) method using pure elemental powders. The microstructure evolution and dissolution of Al₂Cu were studied. The properties of as-hot isostatic pressed composites before and after heat treatment were also investigated. The results show that the prepared Si_P/Al-Cu composites are fully dense. The silicon particles well distribute in Al matrix and still keep the original size. The presence of Al₂Cu, Si and Al is identified in the as-hot isostatic pressed composites. The Al₂Cu phase is formed in the boundaries of the Cu and Al particles. After solution treatment, Al₂Cu phase dissolves into the 70%Si_P/Al-Cu composites, however, some Al₂Cu phase does not dissolve into the matrix of 50%Si_P/Al-Cu composites completely. After the peak-aged treatment, the bending strength of 50%Si_P/Al-Cu and 70%Si_P/Al-Cu composites as-peak-aged is 548 MPa and 404 MPa, which is increased by 38.81% and 13.51% compared with that of as-hot isostatic pressed, the three points bending of the composites can be improved remarkably.