The shapes of spherical HMX particles were studied by digital optical microscope and image manipulation technology. The sphericity of HMX particles were identified and calculated，the average sphere factors of HMX particles are 0.785,0.816,0.790 and 0.810,respectively. The shapes of HMX particles are quantitatively characterized through statistically calculating the sphericity of thousands of HMX particles with particle size of 280-400 μm and 400-450 μm. The results show that this method can distinguish the circularity of different HMX particles and quantitatively characterize the HMX spheroidizing effect.