The illuminating compositions composed of magnesium (Mg), sodium nitrate (NaNO3), Sodium oxalate (Na2C2O4) and binder (Epoxy and Polyamide) were prepared to study the combustion performances, and explored the formulas possessed with both high luminous intensity and low burning rate. The illuminating composition of the Luu-2B/B aircraft parachute flare was adopted as a standard formula with a weight percentage of Mg/NaNO3/binder=61: 30.9: 8.1, and Na2C2O4 was used as an additive agent for reducing burning rate. Furthermore, Taguchi's experimental design method was used to design nine experimental formulas by way of orthogonal array with four control factors and three levels. The experimental results indicated that the optimal formula for long-duration illuminating composition was the Mg/NaNO3 weight ratio of 2:1 (total content 92.9wt.%), the Epoxy-polyamide content of 7.1wt.%, the additional Na2C2O4 of 4 wt. % and the Na2C2O4 particle size of less than150m.