Abstract: Preparation and mechanical and thermoelectric properties were studied for SiC-B₄C composite films. The results show that thermal plasma PVD with SiC and B₄C ultrafine powders as starting materials is a suitable method for the high-rate preparation of SiC-B₄C composite films.The good qualified SiC-B₄C composite films with a layer-by-layer structure were deposited at a maximum deposition rate of 356 nm/s. The micro Vickers hardness of the deposited films increases with the increasing of B₄C content, and the maximum hardness of 35 GPa is obtained. The electrical resistivity and Seebeck coefficient decrease with the increasing of B₄C content, and the maximum power factor at 973 K reaches 640 μWm^-1K^-2 which is 21 times that of sintered SiC.