N-type, P-type modulation-doped Si80Ge20 solid solution alloy and equivalent stoichiometric ratio uniform-doped Si80Ge20 solid solution alloy were prepared by our mature technologies. We concentrated on the thermoelectric properties of both alloy materials. The results show that the power factors of N-type, P-type modulation-doped solid solution alloys are enhanced by 13.6% and 49.2% respectively, compared with that of uniform-doped Si80Ge20 solid solution alloy. And their ZT (thermoelectric figure of merit) are enhanced by 7.9% and 12.9%, respectively