The starting performances of two typical supersonic sidewall-compression inlets were investigated from Mach number 1.5 to 5.0 by means of numerical simulation.The influence of height on performance was studied.The investigation shows that the flow features of inlets with different heights differ a lot during the starting process.For a proper height,the inlet performance prior to startup is improved significantly,oscillations of performance parameters become weaker,and the self-starting Mach number is smaller(a minimum value exists).In such case,the inlet with this height has a better starting performance,and can operate well when the incoming Mach number is less than self-starting Mach number.