As a ideal alloy fuel， Al-5Li alloy can significantly improve the combustion efficiency of propellant with the characteristics of high heat release and micro-explosion during combustion compared with Al. However， Al-5Li alloy powders have high reactivity which is easier to react with the components of propellant， preventing it from being used in propellants directly with some structure related defects， such as pores and cracks. In order to improve the stability and compatibility of Al-5Li alloy， the Al-5Li@7PA samples with high stability and compatibility were obtained through the coating treatment of 7% long-chain alkanoic acid （PA）. The surface is dense and crack-free， and PA molecules adhere to the alloy surface through chemical bonding. The coated samples can be stable in hot water for 30 min. It"s worth noting that the heat of combustion of Al-5Li@7PA samples has an increase of 4.55% compared with the raw Al-5Li. At the aspects of compatibility and chargeability， the compatibility level with HTPB of Al-5Li@7PA samples has increased from level 5 to level 1， and there are no defects such as pores and cracks in the grain column， indicating that the coated Al-5Li alloy meets the propellant charging requirements. Propellant combustion performance test shows that the combustion rate and temperature of Al-5Li@7PA have increased by 10.28% and 45.41% compared with Q3 Al propellant respectively， and the particle size of the combustion product residue is smaller.