The ultrafine aluminum powders with diameter of 1-2 μm were surface grafted by energetic glycidyl azide polymer (GAP) using diisocyanate as bridge via consecutive condensation reactions between —OH and —N＝C＝O groups. The surface properties, compatibility with fluorine polymeric binders as well as resistance to water oxidation of the prepared GAP-grafted aluminium powders were studied. Results show that the static water contact angle of surface of aluminum powders before and after grafting is 0-25.7°and 109.9°, respectively. The surface property of aluminum powders is changed from hydrophilic to hydrophobic after surface grafting. The GAP grafted aluminium powders have better compatibility with fluorine polymeric binders. Moreover, The stability tests for aluminum powders were conducted in water at 70 ℃. 39.8%(mass fraction)of active aluminum are oxidized after 15 min, for the untreated fresh aluminium powders. Only 1.4% of active aluminum are oxidized after 60 min for GAP-grafted aluminum powders, revealing that grafting with GAP can effectively protect the aluminum powders under harsh hydrothermal conditions.