The thermoelectric material can directly convert energy between thermal and electric without involving any moving parts. Due to the limitation in geometry and efficiency of fabricating the thermoelectric modules in conventional methods, additive manufacturing is now becoming a promising solution. Direct Energy Deposition (DED) is superior for its large dimension limitation, fast processing speed, and independence from any powder bed. A physical model of DED fabrication with magnesium silicide (Mg2Si) powder was developed, and validation experiments were conducted. In the model and the experiments, a set of parameters and settings, including laser power, scanning speed, material feeding rate, and so on, were applied to investigate their influences on the products and to validate the simulation. The result of this research can give a reference for the further attempt of DED thermoelectric fabrication.