Abstract: To provide reference data for ultra-micro combustor, a new type button turbojet engine was designed and simulated in the combustion's steady-state process. The boundary condition of inlet was calculated with isentropic numerical calculation taking into account turbulent chemical reaction, heat radiation, and so on, to get the combustion chamber's steady-state of the velocity, temperature and component concentration distribution, to analyze the fuel/air flow and backflow, combustion efficiency and total pressure recovery coefficient, and to compare with the experimental data. The calculation results can accurately reflect the actual combustion. The results show that, when combustion chamber exit velocity is about 65m/s, outlet temperature is around 1000K, the simulation and experimental data are more similar, combustion chamber structure design is reasonable.