The electrical resistivity and thermal conductivity of some Mg-Al, Mg-Zn and Mg-Mn binary magnesium alloys were measured in the temperature range of 2-300K. The electrical resistivity increased with the increasing alloying content in each binary alloy system, while the thermal conductivity exhibited an opposite trend. The low-temperature thermal conductivity was understood using Kappa =(A/T + BT 2)-1 + CT 2, which is found to be applicable in various binary and/or multi-component alloy systems. The parameters A, B and C were determined through numerical fitting of the experimental data. Significant differences were found in the effect of three solute atoms on the thermal conductivity of Mg. The reasons for large differences in the thermal conductivity of the three binary magnesium alloy systems are discussed. Variations in the atomic volume and the valence are believed to play an important role on the thermal conductivity of magnesium alloys.