1,5-Methylene-3,7-dintrio-1,3,5,7-tetraazacyclooctane（DPT） was synthesized by hexamine as primary substance. MgO,NH₄NO₃ and HNO₃ as the system of nitrolysis was used to prepare HMX. The results show that HMX is obtained with a yield of 60.1% at 25 ℃. The conditions is mild and easy to control,the waste solution of reaction is easy to dispose.