The thermal expansion characteristic of explosives under thermal stimulation affects the application of explosives. The thermal expansion characteristic of ［2，2′-bi（1，3，4-oxadiazole）］-5，5′-dinitramide （ICM-101） was studied by using in-situ X-ray powder diffraction， and the thermal expansion coefficient of ICM-101 was obtaind based on Rietveld structure refinement. Results show that there is reversible anisotropic under the high temperature expansion process of ICM-101. In the temperature range of 30-170 ℃， the thermal expansion coefficients of the unit cell parameters a， b， c axis and volume V are 9.19×10^-5 ℃^-1， -9.22×10^-6 ℃^-1， 5.21×10^-5 ℃^-1 and 13.8×10^-5 ℃^-1， respectively. The b-axis exhibits negative expansion characteristics. The unit cell stacking structure of ICM-101 at different temperatures and its correlation with thermal expansion characteristics were studied via the method of molecular spectroscopy technology combined with theoretical calculations. Results show that the compression deformation of the four-membered ring structures of ICM-101 molecules under thermal stimulation is an important reason for the linear negative expansion of the b-axis . Compared with other explosive crystals， the influence of unit cell packing on the thermal stability of explosive crystal structures were analyzed. The thermal expansion anisotropy of explosive crystals with strong hydrogen bonding layered stacked structure is more obvious. When the relative angle between molecules is greater than 100°， the intra-layer hydrogen bonding network affects the interlayer interaction. On the contrary， it will affect the a， b， and c axis directions and limit its thermal expansion.