Abstract: The single-phaseMg₂Si_0.5Sn_0.5Sb_x(0 ≤ x ≤ 0.015) solid solutions were prepared by an induction melting and Spark Plasma Sintering method.The analyzing results of the XRD and XRF shows that this method can effectively avoid the magnesium oxide and control the magnesium content.What's more. the Sb can successfully enter the solid solutions lattice sites.The measurement results of the thermoelectric properties indicate that all the samples of the Seebeck coeficient a are negative and the electrical resistivity? decreases obviously with the increasing Sb-doped,and showing that the solid solutions are ntype conductivity.The Sb-doped solid solutions caused lattice distortion and increased phonon scat. tering,thereby reducing the lattice thermal conductivity.Therefore,the lattice thermal conductivity of Sb doped samples is lower than the undoped sample.The dimensionless figure of merit ZT of Sb-doped samples is obviously higher than the undoped sample,and the ZT for Mg₂Si_0.5Sn_0.5Sb_0.1 sample reaches its highest value of 0.56 at 700K.