Abstract: As for the complex and high consuming in numerical simulations on working condition of cylinder head in diesel engine, a new numerical analysis method was proposed adopting thermo (high temperature gas), fluid (coolant liquid) and solid (mechanical load) multi-physics field coupling method based overall discrete. Analyzing the fundamental and key issues of thermo-fluid-solid coupling, the physical models and finite element model were presented for fluid-solid coupling and heat transferring to get the temperature field distributions of diesel engine cylinder head based overall discrete method. On this basis, the stress field produced from mechanical load was coupled solved, getting the spread of the temperature and stress field on cylinder head under multi-field effects. Based the possible causes analysis, some numerical simulations about thermo-fluid-solid multi-physics field coupling state were given. The results show that, the established governing equation in integral solution method can make the heat transfer boundary be in the solve region and omit iterative between thermo-fluid-solid regions. And the simulation efficiency is improved compared with tradition computing and boundary coupling method.