P-type thermoelectric material Si0.8Ge0.2 was fabricated by mechanical alloying(MA) and Hot-Press Process(HP) The effect of Boron(0.25~2wt%) addition on the thermoelectric properties of p-type Si0.8Ge0.2 alloy was reported. Experiments showed that the electrical conductivity decreased with Boron content at temperature ranging from 500K to 1250K. The carrier concentration measured by the Hall effect measurement also decreased as a function of doping level. With increasing temperature, the Seebeck coefficient and the power factor increased with boron content. Based on measured results, the Figure of Merit (Z) value of 0.5 wt% Si0.8Ge0.2 alloy increased with the small addition of Boron, and reached maximum rapidly; the Z value was 0.9×10-3/K, the highest value among the prepared alloys.