Abstract: As public's demand for the safety of automobile increases, this paper gives a detailed analysis of the thermodynamic model of the brake disc. Firstly, the friction model is elaborated. Then, according to the model, the required parameters are calculated. Finally, the thermodynamic model is analyzed, and the influence of two factors, such as the groove or without and the thickness of the air duct, on the thermodynamic performance of the brake disc is analyzed and compared. The research content of this paper can help the related personnel to strengthen the thermodynamic studies on the automobile brake disc and improve safety for drivers.