Experiments were conducted to study the interstage turbine combustor performance with different inlet air Mach number and the excess air coefficient of cavity.Experimental result shows that total pressure loss increases from 1.5% to 7% varying with the increase of the inlet air Mach number

the flow drag coefficient is 16 which changes little with the inlet air flow Mach number

and overall temperature distribution factor (OTDF) increases with the increase of the inlet air Mach number;OTDF holds the line as the excess air coefficient of cavity increases while the combustion efficiency decreases;the combustion efficiency is almost between 70% through 85%;the maximal lean blow out(LBO) excess air coefficient is 9.7 at the inlet air temperature of 473K.