Abstract: For the fixed geometric inlet operating in a large Mach number rang, a concept of adaptive pressure relief control was proposed to improve the performance. A hypersonic inlet with 2.57 internal contractive ratio controlled by the new technology was studied by numerical simulation and wind tunnel test. The results showed that the inlet had the lower drag, better general and selfstarting performance. And this slot design had little outgassing rate, even selfclosed under higher Mach number. At the same time, the wind tunnel test result affirmed that the limit backpressure capability was improved.