To investigate the effect of α-HMX content on the thermal safety of RDX produced via the acetic anhydride method， and thus addressing a gap in the existing research， five RDX samples （R1-R5） were prepared with α-HMX contents of 0， 9.50%， 12.41%， 17.00%， and 21.68%， respectively. The crystal form of HMX was identified using infrared spectroscopy and scanning electron microscopy. By employing differential scanning calorimetry （DSC） combined with the Ozawa method， Kissinger method， and modelling techniques， we systematically analyzed the thermal decomposition characteristics， kinetic patterns， and storage/transport safety parameters of the samples. Findings indicate that α-HMX reduces the activation energy and decomposition peak temperature of RDX. When the α-HMX content is ≤17.00%， compatibility remains satisfactory and thermal stability is maintained. However， when the α-HMX content reaches 21.68%， the apparent activation energy drastically decreases to 137.29 kJ·mol^-1， compatibility deteriorates， and the self-accelerating decomposition temperature （SADT） drops to approximately 108 ℃， which markedly increases the risk of thermal detonation. Both the RDX and RDX/α-HMX systems follow a three-step sequential reaction model： ‘autocatalysis → N-stage → autocatalysis’. The Ozawa and Kissinger methods can provide initial parameter values for kinetic model fitting. For storage and transportation， there were no significant differences in the SADT among the groups at load capacities of 10， 20 kg and 50 kg. The kinetic model and critical safety parameters established herein provide essential technical support for production control and storage/transport safety in acetic anhydride-based RDX manufacturing， and confirm that the α-HMX content in the product must be maintained below 17.00%.