As improvement of thermoelectric properties of materials based on the phase diagram,this paper describes the thermoelectric properties of Ce-doped Pb1-xCexTe and (BixPb1-xTe)0.88(PbS)0.12 alloys A low thermal conductivity (0.99 ~ 0.696 W.m-1.K-1) was found in the alloy Pb0.95Ce0.05 Te due to the present of the secondary phases Ce3Te4 and Pb,leading its ZT is comparable to that of pure PbTe below 500 K but higher than that of pure PbTe above 500 K.The maximum figure of merit ZT in the alloy Pb0.95Ce0.05Te is 0.88 at 673K in this work,which is higher than that of 0.75 for pure PbTe in the same condition.The thermal conductivity of (PbTe)0.88(PbS)0.12 is as low as 0.99 W/m.K at 300 K and 0.67 W/m.K at 573 K.The Bi doping can change the electron concentrations significantly and thus modify the thermoelectric properties of (BixPb1-xTe)0.88(PbS)0.12 composites.The figure of merit ZT can be enhanced by proper Bi doping.The maximum dimensionless figure of merit ZT of 1.20 is obtained in the sample (Bi0.001Pb0.999Te)0.88(PbS)0.12 at 573K.