p-type Bi0.46Sb1.54Te3 samples containing nanoprecipitates are prepared by mechanical alloying (MA) and spark plasma sintering (SPS) technique. The thermoelectric performance of Bi0.46Sb1.54Te3 is improved by the energy filtering effect induced by nanoprecipitates, leading to a high ZT value of 1.18 at 325 K. To further improve the thermoelectric performance of Bi0.46Sb1.54Te3, SiC nanoparticles are dispersed into Bi0.46Sb1.54Te3 matrix. The addition of SiC simultaneously increases the electrical conductivity and the Seebeck coefficient. Meanwhile, it also decreases the lattice thermal conductivity from 0.38 to 0.33 Wm−1K−1 for the 0.2 wt% SiC sample. Consequently, a maximum ZT value of 1.45 at 325 K is obtained for Bi0.46Sb1.54Te3 with the addition of 0.2 wt% SiC composites, which increases about 23% than the pristine sample.