The pumping performances of double-stage lobe mixer/ejector were experimentally and numerically investigated. The aerodynamic characteristics difference of mixer/ejector between two inlet modes of mixing duct was illustrated and the effects of mixing duct area ratio and length-diameter ratio on the pumping performance of double-stage lobe mixer/ejector were preliminarily analyzed. The results show that the inlet mode of mixing duct has strong influence on pumping capacity. Under the present configuration parameters

the pumping capacity of single-stage lobe mixer/ejector is 10% superior to that of double-stage lobe mixer/ejector in the case of confined inlet. While in the case of open inlet

the pumping capacity is 35% superior to that of confined inlet at most. The pumping capacity of double-stage lobe mixer/ejector is stronger than that of single-stage lobe mixer/ejector. Especially for the mixing duct with bigger area ratio or less length-diameter ratio

the pumping performances of double-stage lobe mixer/ejector in the case of open inlet is superior to that of confined inlet.