The Al-Cr coating exhibits a good steam oxidation resistance and can act as tritium permeation barrier. It is necessary to prepare Al-Cr coating at low temperatures to avoid detrimental effect on the mechanical properties of the substrate. In the present study, a new process was proposed to prepare Al-Cr coating by electrodeposition of Cr/Al composite coatings firstly, and then heat treatment at low temperatures. The Cr/Al composite coatings were obtained by electrodepositing Cr from aqueous solution followed by electrodepositing Al from AlCl3-EMIC ionic liquid. Effects of the temperature of heat treatment on the composition and phase of alloy layers were studied by using OM, SEM, BSE, EDS and XRD. The results showed that an Al-Cr alloy layer at the Cr/Al interface was formed even at low temperature of 540 by the interdiffuse between Al and Cr coating. The different Al-Cr alloy layers could be formed by controlling the thickness of Cr and Al in Cr/Al composite coatings. For 6.5 µm Cr/15 µm Al composite coating, the main phase was Al8Cr5 for 960 min heat treatment at 640 ,a nd for 1.6µm Cr/15 µm Al composite coatings treated at 600 for 30 min, the main phase of alloy layer was Al4Cr.