This paper presents the result of an experimental study on the flowrate characteristics of coaxial swirling injector and coaxial unswirling injector. Effects of the interaction between gas and liquid flows in injector and the change of environmental pressure on the flowrate characteristics of injectors are investigated. The results show that the effect of the interaction between gas and liquid flows is much more significant for coaxial swirling injector than that for coaxial unswirling injector, and that increasing environmental pressure results in the same effects on the gas flowrate characteristics, but effects on the liquid flowrate characteristics for these two type injectors are different.