Thermal conductivity is a key parameter for thermal design and management of the electronic components in their passive cooling processes. In this work, thermal and electrical conductivities of six groups of binary Mg alloys (Mg-Al, Mg-Zn, Mg-Sn, Mg-Zr, Mg-Mn, and Mg-Ca) in as-cast, as-solution, and annealed states were measured and the corresponding microstructures were observed. In both as-cast and as-solution states, thermal/electrical conductivities of the six groups of Mg alloys decreased with composition. Effects of solution treatment and annealing on thermal/electrical conductivities of the as-cast samples were also investigated and discussed. Moreover, the specific thermal/electrical resistivity (thermal/electrical resistivity increment of the alloy derived from one atom addition) of the solute elements for Mg alloys was drawn as follows, Zn < Al < Ca < Sn < Mn < Zr. Atomic volume difference of the solute elements with Mg atom (Delta V/V (Mg)), valency, and configuration of extra-nuclear electron of the solute were believed as the main reasons for the differences.