Pyrotechnic compositions containing magnesium (Mg) powder face the problem of degradation by moisture. Although potassium dichromate is an effective stabilizer that avoids Mg degradation, it is detrimental for human health and environment. This study is aimed at developing a harmless stabilizer for Mg in pyrotechnics. We investigated the effect of magnesium stearate (MgSt) coating on stabilization and combustion properties of the coated Mg. The stabilization effect of MgSt coating was measured by aging test of ammonium perchlorate (AP) and Mg mixture (AP/Mg). The aging test revealed that MgSt coating reduced the generation of degradation product, Mg(OH)(2). Results of burning test showed that MgSt has little effect on flame color, while it considerably decreased the burning rate. The influence of MgSt coating was lower than that of MgSt that was simply mixed with AP/Mg.