The study of Mg2Si/C composites as anode materials for lithium ion batteries is reported in this paper. Firstly, Mg2Si was synthesized by mechanically activated annealing (MAA) technique and the preparing conditions for pure Mg2Si alloy were investigated and optimized. Then the composite materials of Mg2Si and carbon materials such as CNTs and CMS with different ratios were prepared by the followed ball-milling techniques. Their electrochemical performances were compared by the galvanostatically charge/discharge and EIS experiments. The pure Mg2Si alloy delivers a large initial capacity, but the capacity decreases rapidly with cycling. In contrast, the composites show good cyclic stability and deliver a reversible capacity of about 400mAhg−1 with 40% carbon in the composite. The results of EIS indicate that the composite of Mg2Si/CMS has better interface stability than that of pure Mg2Si materials.