Two general expressions and their six derived formulae for estimating the critical temperature(Tb) of thermal explosion for energetic materials(EMs) were derived from the Semenov's thermal explosion theory and eight non-isothermal kinetic equations via reasonable hypothesis. We can easily obtain the values of the initial temperature(T0i) at which DSC curve deviates from the baseline of the non-isothermal DSC curve of EMs, the onset temperature(Tei), the exothermic decomposition reaction kinetic parameters and the values of Too and Te0 from the equation Toiorei=Tooore0+α1β1+α2β2+...+αL-2βi^L-2, i=1, 2, …, L and then calculate the values of Tb by means of the six derived formulae. The results obtained with the six derived calculating methods for six trinitromethyl explosives: bis(2,2,2- trinitroethyl-N-nitro) ethylene diamine(BTNEDA), 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate(TNETB), bis(2,2,2- trinitroethyl) formal(BNTF), bis(2,2,2-trinitroethyl-nitramine)(BTNNA), 2,2,2-trinitroethyl-2,2,2-trinitroethyl-N- nitroamino acetate(TNTNNA) and tetrakis [2,2,2-trinitroethyl] orthoester(TTNOE) agree well with each other.