Based on the empirical electron theory (EET), of solid and molecules analysis is made on the Al2Ca, Mg2Ca and Al4Ca intermetallic compounds in Mg-Al alloys containing Ca and the valance electron structures (VES) of these compounds have been calculated. According to the calculative results, bond networks of these compounds have been set up. The analysis and calculation made on these intermetallic compounds with EET shows that the bond network of Al2Ca has high bond energy and the differences of the bond strength between different crystalline directions is not remarkable, so that its stability is the highest among the three structures studied. Both Al4Ca and Mg2Ca have weak bonds or weak bond zones that leads to breakage easily, which accounts for the low stability of the structure. (C) 2002 Elsevier Science B.V. All rights reserved.