alpha- and gamma-alumina (alpha-Al2O3 and gamma-Al2O3) are used to model the surface oxide layer of AlH3 to investigate the micro-mechanism for the interactions of three energetic plasticizers: Bis-2,2-dinitropropyl formal (BDNPF), N-butyl-N-(2-nitroxyethyl) nitramine (BuNENA) and nitroglycerin (NG) with AlH3 surface oxidation layers. First principle density functional theory (DFT) calculations with all-electron double numerical basis functions (DND) are employed. It is found that three energetic plasticizers can be strongly adsorbed by the oxide film of AlH3 and release a large amount of heat. Moreover, BuNENA and NG containing -ONO2 groups easily undergo barrierless decomposition reactions on the alpha-Al2O3 (0001) surface and spontaneously produces NO2 radicals, causing significant changes in the structures of BuNENA and NG molecules as well as of the alpha-Al2O3 (0001) surface. Furthermore, NG can also undergo a barrierless decomposition reaction on the gamma-Al2O3 (110) surface. However, BuNENA does not decompose on the gamma-Al2O3 (110) surface, and it is not easy for BDNPF to decompose on either alpha-Al2O3 (0001) or gamma-Al2O3 (110) surfaces; hence, it remains relatively stable. According to these results, it is suggested that the order of compatibility among the three energetic plasticizers with AlH3 is BDNPF > BuNENA > NG.