The mathematics expression of apparent activation energy of thermal decomposition reaction calculated from integral isoconversional non-linear (NL-INT) method was derived from the evaluation function when decomposition extent α was the same value from non-isothermal decomposition kinetic equation. The thermal decomposition apparent activation energy of HMX, HMX based PBX,TATB,PETN explosives and F₂₃₁₄, SD-33 bonders were calculated by NL-INT method based on the TG curves at heating rates of 5,10 and 20 K·min^-1,respectively,and the results calculated by NL-INT method and Ozawa′s method were analyzed and discussed. Results show that the method can conquer errors caused by approximation of temperature integral and choice of mechanism function, and the apparent activation energy obtained were more nicety.