The mixture and composite of dihydroxylammonium-5，5"-bistetrazole-1，1"-diolate （HATO） and ammonium perchlorate （AP） were prepared by dry-mixing and solvent-nonsolvent recrystallization， respectively. The microstructure and mechanical sensitivity of HATO， AP， HATO+AP mixture and HATO-AP composite were analyzed by scanning electron microscope （SEM） and military standard methods， and the ignition and combustion pressure characteristics of four materials mentioned above were also compared experimentally. In addition， the reaction characteristics of HATO-AP composite was discussed based on the thermogravimetry-mass spectrometry （TG-MS） results. Results show that HATO and AP may be cocrystal， crystal mixed or coated with each other in HATO-AP composite， which makes the mechanical sensitivity of HATO-AP composite significantly lower than that of HATO+AP mixture. The peak of combustion pressure and pressurization rate of HATO are much higher than that of AP. The HATO-AP composite can eliminate the adverse effects of AP in combustion property， and increase the peak of combustion pressure by 17.3% compared with raw. Because of the intimate contact between HATO and AP on a smaller microscopic scale in the composite， this allows these two molecules to react directly. The N element may directly react to form NH₃， HCN， NO or other NO_x instead of N₂ in the reaction process. The changes in reaction mechanism may make a difference on combustion pressure characteristics of HATO-AP composite.