Thermal energy generated by the friction between the disc and pad is transferred to both components and causes thermal expansion of material of each component, and futher affects the friction contact condition. This is the main factor of the thermoelastic instability (TEI) of a disc brake. In this study, TEI is analyzed using the finite element analysis technique. Three dimensional thermo-mechanical analysis model of the disc brake system is created. An intermediate processor based on the staggered approach is used to exchange analysis results: temperature, friction contact power, nodal displacement and deformation. Disc thickness variation (DTV) and temperature distribution of the disc are calculated, and the tendency and meaning of the results are discussed.