With the help of the initial temperature(T₀), at which DSC curves deviate from the basline, the onset temperature(T_e) and maximum peak temperature(T_p) from the non-isothermal DSC curves at different heating rates(β), the thermal decomposition activation energy(E_K and E_O) and pre-exponential constant(A_K) obtained by Kissinger′s method and Ozawa′s method, the value of b_{e0(or p0)} from Hu-Zhao-Gao′s equation and the value of a_{e0(0r p0)} from Zhao-Hu-Gao′s equation, the values of specific heat capacity(C_p) obtained by microcalorimetry, density(ρ) and thermal conductivity(λ), the decomposition heat(Q_d, taking half-explosion heat), Zhang-Hu-Xie-Li′s formula, Hu-Yang-Liang-Xie′s formula, Hu-Zhao-Gao′s formula, Zhao-Hu-Gao′s formula, thermodynamic relation formulae, Smith′s equation, Friedman′s formula, Bruckman-Guillet′s formula, Frank-Kamenetskii′s formula， Wang-Du′s formulas and Yoshida′s formulas, the values(T₀₀, T_e0 and T_p0) of T₀, T_e and T_p corresponding to β→0, thermodynamic parameters of activation reaction(ΔG^≠、ΔH^≠、ΔS^≠), thermal explosion temperature(T_be0 and T_bp0), adiabatic time-to-explosion(t_Tiad), 50% drop height(H₅₀) of impact sensitivity, critical temperature of hot-spot initiation(T_{cr, hot-spot}), critical ambient temperature of thermal explosion(T_acr), safety degree(S_d), thermal explosion probability(P_TE), explosion potential(E_p) and shock sensitivity relative to m-dinitrobenzene(S_S) of 1,1′-Dimethyl-5,5′-azotetrazole monohydrate(1, 1′-DMATZ) and 2,2′-Dimethyl-5,5′-azotetrazole(2, 2′-DMATZ) are calculated. The results show that(1) 1, 1′-DMATZ is thermally stable;(2) the heat-resistance ability of 1, 1′-DMATZ is better than that of 2, 2′-DMATZ; (3) the different positions of the methyl group in the molecules are the principal factor affecting the thermal safety.