Abstract: The thermal stability of N, N-dimethylhydroxylamine(DMHAN) in the nitric acid solution was studied using micro calorimeter. The main influence factors including the nitric acid concentration, the concentration of DMHAN, MMH, atmosphere(air and nitrogen) and metals were studied and compared the thermal stability of DMHAN with HAN under the same conditions. The results show that the initial reaction temperature(t₀) of DMHAN/HNO₃ (HNO₃: 1.5-3.0 mol/L, DMHAN: 0.05-0.8 mol/L) is improved as the acidity reduces or the concentration of DMHAN increases. The reaction heat of DMHAN/HNO₃ is 865.5 kJ/mol and 683.4 kJ/mol respectively when the mole concentration ratios of HNO₃ to DMHAN are 2.5-10 and 12.5-20. This indicates the different ratio of HNO₃ to DMHAN makes the scale of reactions different in the DMHAN/HNO₃, so it makes the different reaction heat. Holding reductant MMH make the induction period of the autocatalytic reaction become longer. The air, nitrogen atmosphere, Fe and the fission products (Zr, Ru) do not affect the decomposition of DMHAN, but the stainless steel make the DMHAN/HNO₃ show higher reactivity.