A new high-energy organic magnesium salt [Mg(H2O)(6)](BTATz)center dot 2H(2)O[BTATz=3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine] was synthesized and characterized by elemental analysis and Fourier transform infrared(FTIR) spectrometry. Its crystal structure was determined by X-ray single crystal diffraction. The crystal belongs to monoclinic system with space group C2/c and a=2.1329(7) nm, b=0.52275(16) nm, c=1.5909(5) nm, beta=100.471(6)A degrees, V=1.7443(9) nm(3), Z=4, A mu=0.361 mm(-1), F(000)=900 and D (c)=1.644 g/cm(3). Meanwhile, the thermal behavior of [Mg(H2O)(6)](BTATz)center dot 2H(2)O was studied under the non-isothermal conditions by differential scanning calorimetry( DSC) and thermalgravity-differential thermalgravity(TG-DTG) methods. The enthalpy, apparent activation energy and per-exponential factor of the main exothermic decomposition reaction are 898.88 J/g, 139.2 kJ/mol and 10(10.48) s(-1), respectively. The values of the self-accelerating decomposition temperature(T (SADT)), the thermal ignition temperature(T (TIT)) and the critical temperature of thermal explosion(T (b)) for [Mg(H2O)(6)](BTATz)center dot 2H(2)O are 515.13, 532.08 and 565.99 K, respectively.