The kinetics of precipitation in A1-06Mg-09Si-02Cu (mass fraction %)alloy under different conditions was investigated饰differential scanning calorimetric analyses (DSC) and micro- hardness measurements The results show that  an exothermic peak at about 100-150℃can be observed in the DSC curve for the nature aged (T4) alloy  but no peak for the pre-aged (T4P) alloy  and the peak corresponding with β"phase moves toward the low temperature zone for T4P alloy