Abstract: A GH 2/LO 2/RP-1 injector is an important component of a tripropellant rocket engine.Four types of tripropellant injector were employed to conduct the flowrate characteristics test.The regularities of the injectors' mass flowrate variation with each propellant injection pressure drop were studied;the effects of the injectors' configuration on the flowrate coefficient were analyzed,the injectors' flowrate characteristics in tripropellant operating condition were compared with those in bipropellant operating condition;the pressure of the dual-fuel premixed cavity of the swirl injector with premixed fuel injection was measured and the flowrate characteristics of the injector were analyzed.The conclusions obtained in this paper provide an important reference for the optimization design of the tripropellant injectors and the gas/liquid coaxial injectors.