SiC-Si composite, that is stable in oxidizing atmosphere at 1300 degrees C and has thermal shock resistance, was prepared from a powder mixture of porous beta-SiC, which was prepared from rice hulls, and Si metal. To use an SiC-Si composite as a structural support for a high temperature combustion catalyst, the foaming SiC-Si composite form with continuous bubbles was prepared from foaming SiC form and the mixture of the porous beta-SiC and Si metal. The foaming SiC form was prepared from the foaming polyurethane form and a beta-SiC fine particles. The beta-SiC fine;particles having an average diameter of 0.3 mu m was coated on the foaming polyurethane form. The polyurethane part of the form was burned out and the coating beta-SiC was sintered to form the foaming SiC form. The SiC form was coated on the porous SiC and Si metal powder mixtures and was heated at 1500 degrees C in argon to prepare the foaming SiC-Si composite. The foaming composite was stable in an oxidizing atmosphere at 1300 degrees C and was highly resistance to thermal shock. The compression stress of the foaming SiC-Si composite form (175 kg/cm(2)) was about twice that of the a-axis of honeycomb-shaped cordierite (> 85 kg/cm(2)).