An oblique baffle was set behind the high temperature and high speed airflow nozzles in order that the air can flow along the baffle into the surrounding environment to decrease the affection around relevant personnels and equipments.For ensuring the use of the baffle, the heat transfer was analyzed and it was found the air layer on the baffle surface is the dominant factor.And the boundary layer stability is affected by the surface roughness and the baffle top edge angle.The influencial factors and their coupling characteristics under different operating conditions were studied by using the software FLUENT.The results show that the proper coating surface roughness can reduce the heat flux by 3%~7%, and the temperature of top surface of baffle by 10%.