Mg(2)Sn is a well known anode material used in rechargeable lithium batteries, and a principal component of low melting tin-based alloys. In order to improve its anodic as well as anti corrosion performance, alloying of selected metals like aluminum into Mg2Sn was recommended in the literature. In this research,phase stability of a series of tin based (Mg(x)Al(1-x))(2)Sn alloys was studied by DFT calculations. Structural and thermodynamic properties of Al in Mg(2)Sn was disclosed, which may be of interest to the design of new anode materials or low melting alloys for industrial applications.