Preparation method of HMX

The invention discloses a preparation method of HMX. The preparation method comprises the steps of dissolving dinitrogen pentoxide into an organic solvent to form a nitrating agent; slowly adding ammonium salt into the nitrating agent, and adding DPT in batches to obtain reactants; controlling the temperature of the materials to be 0-10 DEG C in a feeding process, heating the reactants up to 20-35 DEG C, and carrying out a reaction at the constant temperature for 20-60min; after the reaction is finished, carrying out solid-liquid separation to obtain solid; washing the obtained solid, drying in the air, and purifying to obtain the HMX, wherein the organic solvent is selected from acetonitrile and dichloromethane, and the ammonium salt is selected from tetramethyl ammonium chloride, ammonium carbonate, ammonium acetate and ammonium oxalate. The preparation method provided by the invention is mild in reaction conditions and easy in separation of products, and needs a less amount of acid; the system does not pro