Abstract: SiGe alloy is a kind of thermoelectric material with great potential in high temperature region.In the silicon germanium alloy system,the thermoelectric properties of p-type SiGe alloy series thermoelectric materials are relatively low.In order to improve the thermoelectric properties of p-type SiGe alloys,the most effective method is to introduce appropriate second-phase atoms for doping.Al was doped into Si_0.85Ge_0.15,and the bulk samples Si_0.85-xAl_xGe_0.15（x=0,0.015,0.020,0.0250.030） were prepared by arc melting and hot pressing.The effect of main element doping on the thermoelectric properties of the materials was investigated.The results show that the carrier concentration is significantly increased and the thermoelectric properties of the material are improved after the partial substitution of Al for Si.The power factor of Si_0.85-xAl_xGe_0.15（x=0.015） increases to 0.9×10^-3W·m^-1·K^-2at 900 K,which is about 8 times higher than that of the undoped sample.The ZT value of the alloy samples also increases with the doping of Al,and the ZT value of Si_0.85-xAl_xGe_0.15（x=0.015） is raised to the maximum of 0.18 at 900 K.