Abstract: When the engine is working normally, the high temperature exhaust gas is directly in contact with the inner wall pipe of the exhaust manifold, causing large thermal deformation to the exhaust manifold and even leading to damage. In this paper, the heating condition of exhaust manifold of a four-cylinder engine is analyzed. The finite element method is used to simulate the normal operation of exhaust manifold by setting the boundary conditions and the external environment parameters. In order to explore the factors affecting the change of exhaust manifold temperature, the change of exhaust manifold temperature is observed through changing the internal fluid temperature and velocity, as well as the value of convective heat transfer coefficient. The factors that may affect the heating of exhaust manifold are analyzed and compared.