Abstract: The quest for higher stage pressure ratio has been promoted by engine researchers.But in the multi stage fan and compressors,the rise in total and static pressures of a single stage axial flow compressor is constrained by many factors.The maximum stage loading level has a limitation.Using a simplified stage model,this paper investigates this level of a super or tran sonic single stage axial flow compressor under the conditions of the widest rotor stator matching and the stage matching.The paper concludes that the stage pressure ratio must be less than 37 when considering only the theoretical loading mechanism.Meanwhile it gives several graphs to exhibit the influencing strength of each constraint.