In an attempt to lower the ignition temperature of the combustion synthesis of MoSi₂, the synthesis was conducted using elemental Mo and Si powder mixtures prepared by mechanical alloying. The mechanical alloying resulted in powders with microstructure of alternating layers of Mo and Si phases. The ignition temperature of the combustion synthesis for the mechanically alloyed powders was measured to be around 670℃, which is almost 550℃ lower than that for the powder mixture prepared by low energy ball milling. A mathematical model is developed to explain the decrease in ignition temperature for the powders prepared by mechanical alloying. Based on the mathematical model, the effects of mechanical alloying time on the ignition temperature as well as the combustion behavior are discussed.