Abstract: This paper analyzes the structure and oil circuit of the transmission system of a bulldozer, and determines the main heat source of the system. By simulating the working condition of the bulldozer, the calorific value of the transmission system of the bulldozer is calculated quantitatively, the structure and mechanism of the heat dissipation in the transmission system are analyzed, and the heat dissipation quantity is calculated quantitatively, the heat balance temperature of the transmission system of the bulldozer is calculated. A set of heat balance analysis software which can be used in the transmission system of the same bulldozer is developed.