The current study obtained contributions of individual process factors and optimal factors for hardness and UTS, in the heat treatment process of Al-Cu-Mg alloys, every factor such as Mg content, solution temperature, aging temperature and pre-aging time, has three levels, respectively. The standard experiment layout 3 level orthogonal array (OA) L9 was considered. The interaction between the parameters was neglected. Solutionization is conducted at a temperature high enough to put in solution the alloying elements and obtain a supersaturated solid solution, which, in the case of Cu and Mg, is normally at 510 to 550°C. This is the typically know as the "solution temperature". In recent times, the forming of various automobile body panel parts often involved the application of various temperature 170 °C, 180 °C and 190 °C of ageing which in turn would influence the ageing characteristics of the alloy. Taguchi method puts emphasis on S/N ratio as opposed to simple average of output. Analysis of Variance was used to investigate percentage Contribution of Each process parameters on output Response. Results show that parameters such as % Magnesium addition and ageing duration has significant effect on mechanical properties