Abstract: When the manned spacecraft is in a pressure emergency condition, one may see low pressure and rich oxygen, In order to analyze the fire hazard on the manned spacecraft’s orbital flight and the ground simulation test, a combustion chamber which can simulate the oxygen-rich and reduced-pressure is developed. This paper analyzes the materials’ flame propagation rate and the threshold ignition energies of manned spacecraft in the pressure emergency condition, and the flammability characteristics of materials. Recommendations for fire preventions are proposed.