Under non-isothermal condition, the thermal behavior of pentaerythritol diazido dinitrate (PDADN) is studied using TG, DSC, pressure DSC and the simultaneous device of the solid reaction cell in situ/rapid scanning Fourier transform infrared (RSFT-IR) spectroscopy. The results show that (1) the extrapolated onset temperatures (T-e), peak temperatures (T-p) and enthalpy of decomposition (Delta H-dec) increase obviously with the change of pressure from 0.1 to 2 MPa. Over the range of pressure from 2.0 to 6 MPa, the thermal behavior of PDADN does not seem to be obviously affected by the pressure; (2) the apparent activation energy, pre-exponential constant and the most probable integral mechanism function of thermal decomposition of PDADN at the pressure of 0.1 MPa are 134.9 kJ mol(-1), 10(12.7) s(-1) and 1-(1-alpha)(3), respectively; (3) the experimental values of pressure are a principal factor affecting the magnitude of the apparent activation energy; (4) the mechanism of thermal decomposition of PDADN can be expressed by the following scheme: [GRAPHICS] (5) the critical temperature of thermal explosive for PDADN is 423.74 K.