Abstract: An experimental and theoretical study on the flowrate characteristics of gas-liquid coaxial atomizers in hydrogen/oxygen rocket engine are presented in this papaer.The dependence of the gas and liquid flowrates of atomizers with different recess ratio on the injection pressure drops was determined by the tests with air and water.The effect of the interaction between gas and liquid flows within atomizer on the flowrate characteristics was investigated experimentally.The results show that the interaction between gas and liquid flows has a certain effect on the flowrate characteristics,and the effect is greater for the atomizers with larger recess ratio.A simplified theoretical model is developed to calculate the flowrates of gas-liquid coaxial atomizers.The comparison between the theoretical and experimental results shows a reasonable agreement.