In order to study the effect of the crystal microscopic properties of elemental explosives on their macro-mechanical behavior and impact sensitivity of composite explosives， the micro-plastic characterization methods of TNT， RDX and HMX were studied. And the correlation analysis between the micro-plasticity of the explosive crystals and their impact sensitivities of the elemental explosive was carried out. Nano-indentation technology was used to test and calculate the micro-elasticity and micro-plasticity of TNT， RDX and HMX explosive crystals， and a calculation method based on the ratio of plastic energy and indentation energy （η_P） was proposed to quantify the micro-plastic properties of explosive crystals. The results showed that， compared with the micro-plasticity （δ_h） calculated by the indentation depth， the linear correlation coefficient between the micro-plastic properties （η_P） of the explosives crystals obtained in this research and impact sensitivities （P） of explosives in simple powders reached 95.8%， or micro-plastic properties of simple explosives were highly related to their impact sensitivities on the micro-characterization method of plastic properties of explosives crystals proposed in this paper. This research provided a micro- characterizing method for evaluating safety levels of explosives.