A car engine-thermoelectric source system is constructed. The simulation procedure of the system shows in the following. With the using of AVL-BOOST software, the Operating condition of this system is simulated according to the structure of the engine and the temperature, velocity, pressure of the exhaust are obtained, which are used as the initial conditions of the thermal power. The geometry and mathematical model of thermoelectric generator is established and numerical calculation is done with the Star-CD software. This paper focuses on a type of four-stroke gasoline engine-intramural thermoelectric system and gives a calculation instance of the generator’s components.