The thermal safety of 2,4-dinitroanisole(DNAN) explosive was studied by cook-off test. The self-ignition temperature,the delay time of thermal explosion and the critical temperature for the thermal explosion of DNAN were obtained,and the test results were compared with that of TNT. The results show that the self-ignition temperature of DNAN is 346.7 ℃,the temperature of 5 s explosion point is 374.1 ℃, and activation energy is 48.37 kJ·mol^-1. Under the ambient temperature of 220 ℃,when DNAN is placed for 48 h, DNAN is nonflammable. DNAN is semi-burned under the ambient temperature of 230 ℃. When the temperature reaches above 240 ℃, thermal decomposition reaction of DNAN occurs. The delay time of thermal explosion was obtained from theoretical calculation at 100 ℃. Results show that DNAN is stable and safe in the melting process of temperature below 100 ℃.