In order to solve the problems of low density and effective oxygen content of the existing oxidant NH₄ClO₄ （AP） for mixed explosives， the oxidant KClO₄ （KP） with higher density and oxygen content was compounded with AP， and the optimal ratio of AP/KP composite oxidant was determined by Molecular Dynamics. The novel AP/KP composite oxidant with high density and high oxygen release was prepared by physical mixing and solvent evaporation method， respectively， and its elemental composition， morphology， structure， composition and thermal properties were characterized by inductively coupled plasma spectrum generator （ICP）， scanning electron microscope （SEM）， X-ray powder diffractometer （XRD） and thermal analyzer （DSC-TG）. The results show that element and particle size distribution of the AP/KP composite oxidant prepared by solvent evaporation method is reasonable and uniform. The crystal form has not changed， and the crystal form is relatively complete， as proved by XRD. The thermal decomposition peak temperature of AP and KP was decreased by 11.25 ℃ and 13.87 ℃， respectively， which was more conducive to the thermal decomposition process. In addition， the composite oxidants prepared by physical mixing and solvent evaporation method were introduced into typical metal combustible agent Al powder， the ignition and combustion properties of samples prepared by different methods with Al powder were compared and studied. The results show that when the AP/KP composite oxidant prepared by solvent evaporation was mixed with Al powder， the combustion calorific value reached 12.228 MJ·kg^-1， and the pressurization rate reached 5.21 MPa·s^-1. The laser ignition test shows that the shortcomings of slow AP combustion reaction rate and difficult KP ignition were greatly improved.