To fabricate Tritium Penetration Barrier (TBP) of aluminide coating on stainless steel, aluminum electrodeposition experiments on the HR-2 stainless steel were carried out by ambient temperature chloroaluminate melts AlCi3(aluminum chloride)/EMIC (1-ethyl-3-methylimidazolium chloride) under the protection of argon gas. The influences of pre-treatment of the substrate and the current density on the surface morphology, purity and adhesion of the aluminum coating were examined. The results show that the aluminum electrodeposition on HR-2 stainless steel by ambient temperature melts system AlCl3/MEIC is feasible. The aluminum coating on the HR-2 stainless steel substrate with conventional pretreatment is of high quality but the adherence to the substrate is not good. However, electrochemical etching of the substrate by anodic polarization prior to electroplating leads to well-adherent Al coating of HR-2 stainless steel. The deposited aluminum coating is white, smooth, uniform and dense, having the characteristics of irregular sphere particle-like growth with certain edge angle. The particle size of the aluminum coating increases with increasing current density. The preferable range of current density is 10-20 mA/cm2, and the electroplating time is 40 min at least.