1,4-Diamino-3,6-dinitropyrazolo[4,3-c]pyrazole(DADNP) was synthesized by N-amination reaction, and its structure was characterized by NMR, IR, MS and element analysis. The thermal decomposition kinetics and mechanism were studied by means of different heating rate differential scanning calorimetry(DSC), rapid-scan fourier transform infrared spectroscopy(RSFTIR) and thermogravimetry-mass spectrometer(TG-MS) coupling technique. The results show that the apparent activation energy and pre-exponential constant of the exothermic decomposition reaction of DADNP obtained by Kissinger method are 166.45 kJ·mol^-1, 1016.53 s^-1. The decomposition of DADNP includes two stages, which begins with the rupture of C─NO₂ with subsequent loss of NO₂ under electron impact and heating condition, respectively. In the first stage of decomposition, the rupture of one C─NO₂ and one pyrazole ring in DADNP molecule with the release of NO₂ and N₂H₂ occur under electron impact condition, whereas the homolysis of two C─NO₂ bonds occur with the loss of two molecular NO₂ under heating condition.