To explore the detailed thermal decomposition properties of the mixture system consists of ammonium perchlorate-based molecular perovskite energetic material （H₂dabco）（NH₄）（ClO₄）₃ （DAP-4， where H₂dabco²⁺ refers to 1，4-diazabicyclo［2.2.2］octane-1，4-dianiumion） and dihydroxylammonium 5，5"-bistetrazole-1，1"-diolate （TKX-50）， the thermal decomposition characteristics and gas products of DAP-4 and DAP-4/TKX-50 mixtures were comparatively analyzed by using differential scanning calorimetry-thermogravimetry/mass spectrometry/fourier infrared spectroscopy； meanwhile， the changes of characteristic groups in the condensed phase of DAP-4 and DAP-4/TKX-50 mixtures with temperature were investigated by in-situ FTIR. Based on the explorations the thermal decomposition mechanism of DAP-4/TKX-50 mixture was proposed. The results showed that after mixing DAP-4 with TKX-50， DAP-4 had little effect on the thermal decomposition of TKX-50， while the heat generated by the thermal decomposition of TKX-50 made the reversible phase transition endothermic peak of DAP-4 disappeared， but hardly affected DAP-4′s thermal decomposition at high temperature. The thermal mass loss of DAP-4/TKX-50 mixture was divided into two stages. The mass loss of the first stage was 43.4% and the mass loss of the second stage was 52.4%， leaving 4.2% of the decomposition residue. The main gas products produced by thermal decomposition of DAP-4 and DAP-4/TKX-50 mixture were NH₃/H₂O/HNCO/HCN/CO/HCl/CO₂ and H₂O/NO/N₂O/HCl/NH₃/N₂/HNCO/HCN/CO/CO₂， respectively. The thermal decomposition mechanism of the DAP-4/TKX-50 mixture was proposed as follows： the reversible transfer of hydrogen ions occurs first in the molecule of TKX-50 to generate hydroxylamine and 1，1"-dihydroxy-5，5"-bitetrazole （BTO）， then hydroxylamine decomposed into small molecular gases at high temperature while the fragments generated by BTO decomposition partially polymerized into coupling products. Finally， the ionic bond of DAP-4 was broken， leading to instantaneous collapse of the cage-like skeleton. The strongly reducing and strongly oxidizing gas components underwent violent redox reactions at high temperatures and release a large amount of heat.