HMX with round and smooth crystal particles was prepared by improving solvent etching,and was compared with raw HMX. Their particle sizes and morphologies were characterized with optical microscopy (OMS),scan electron microscope (SEM) and laser particle size analyzer,and packing densities were tested by standard vessel method,and thermal and mechanical properties were tested by differential scanning calorimeter (DSC) and the compressive stiffness test (CST). Results show that rounded HMX is round and smooth,the characteristics such as the powder size distributions,thermal properties and mechanical sensitivity do not change,while packing density is increased by 13% and mechanical properties are obviously improved.