Through the calculation of the flow rate distribution, wayside parameter and wall temperature distribution of engine flame tube under the conditions of high altitude and low velocity, the cooling characteristic of the engine combustion chamber is analyzed and investigated. The results show that, under the conditions of high altitude, the flame tube wall temperature of the same axial position is increased with the increase of Mach number; and the film cooling has a finite effective length of cooling protection, which makes the flame tube wall temperature distribute axially in a saw-tooth curve.