Abstract: This paper introducethebasic principles of grith compressed air ejector, which mainly studied the effect of different material and thickness of the gap adjusting shims on the performance of the ejector device, meanwhile study the influence of working pressure, surface shape of the intake of air collector, flange arc radius on the influence of air volume and air inflow of ejector ,the result show that the material of shim have a big influence on the import volume of ejector， effect will be the best when the shape of the intake air collector is conical and the more suitable range of the flange arc radius is 4-8m, should make full use of ejector’s optimal performance during the actual use process.