Abstract: The intake with plenum bypass is a new type subsonic intake for civil medium range aircraft.Its geometry is considered.A model of this type has been designed,which scale is 1∶2.Experiments of flow visualization,gasdynamic performance and foreign object throwing have been done.The experimental results show that its perfect gasdynamic performance and flow steadiness satisfy the requirements of aeroplane and engine.Compared to the intake with pipe by pass,this new type intake has many advantages,especially the improved ability of eliminating the foreign object,although the total pressure coefficient of this type intake slightly lessens.This type intake has extensive application in the future to the civil aviation with the strict requirements of airworthiness.