The paper aims to select a type of modified HDPE plastics for replacement to solve some obvious disad-vantages including complicated structure, high weight and difficulty to adapt to the automatic packaging process of current packaging materials for gun propellants. The compatibility of the modified HDPE with typical gun propellants was investigated with differential scanning calorimeter and vacuum stability test device. The mechanical performance change of the modified HDPE was tested by accelerated thermal aging test and its thermal aging life was predicted. The changes of the internal ballistic properties of the gun propellant packaged with the HDPE plastics after road transportation for 500 km and free fall were identified through ballistic firing test. The results showed that the modified HDPE was fully compatible with the typical gun propellant. There was no obvious change to the tensile strength and the impact strength tended to decrease after the accelerated thermal aging test. The average thermal aging life was 17.51 years at a storage temperature of 25 ℃. After transportation and free-fall test, the gun propellant was well protected by package from the modified HDPE plastics and no obvious changes occurred to the interior ballistic properties of the gun propellant. Modi-fied HDPE plastics can be used as main material of plastic packaging for gun propellants.