Thermal stability of explosive mixture containing solid-liquid phase of trinitrohexahydrotriazine (RDX), isopropyl nitrate (IPN, 2-propyl nitrate) and aluminum powder (Al) with addition of different rates of 5%, 10%, 15% and 20% of sulfuric acid H2SO4 to the (RDX/IPN/Al) mixture was measured based on numerical simulation. Kissinger, equation of state (EOS) method and Maxwell approximation were used to compute the physic-chemical characteristics of the mixture. We add an amount of acid to present a new explosive component. To obtain the ignition temperature, Cookoff model of cylindrical test is performed. The heating process of mixture at different ambient temperatures was progressed, and the ignition temperature was found that it depends on both acid rate added and different ambient temperatures applied and focused by SADT analysis. Temperature distributions over time, different ambient temperatures effect on ignition delay time, ignition position are carried out.