Abstract: Different solution-ageing processes were carried out by way of orthogonal experiment for the semi-solid Al-Cu-Mn alloy forgings. Then, the resultant hardnesses were analyzed to determine the optimal technological parameters in such a heat-treatment, with the microstructure after ageing discussed. It was revealed that the Vickers hardness number can come up to over 130 MPa if the temperature/time of solution hardening and of age hardening are 540°C/13 hr and 165°C/8 hr, respectively, with the precipitated phases distributed uniformly and dispersedly on the matrix.