Under submerged condition, due to the external static pressure at nozzle exit, the cross section and inflow pressure of ejector pipe have significant impact on the suction performance and energy dissipation of annular jet device. In order to better adjust the annular jet nozzle, the methods of numerical simulation and experimental validation were adopted to analyze the impact of different cross section ratios and different inflow pressures on nozzle’s inspiration capacity and gas liquid ratio. From flow field, the energy dissipation and the intensity of vortex were explained for these effects. Results showed that both inspiration capacity and gas liquid ratio were increased in low cross section ratio, but in high cross section ratio inspiration capacity was decreased while gas liquid ratio was increased firstly and then decreased with the increase of inflow pressure, thus the ratio got the maximum value in this case. With the increase of cross section ratio, the inspiration capacity was increased while the gas liquid ratio was decreased. Different inflow pressures had good controllability for the gas liquid ratio with low cross section ratio, meanwhile, different cross section ratios had remarkable controllability for the gas liquid ratio at high inflow pressure. Under the same kinetic energy increment, the turbulent dissipation rate increment at different cross sections was considerably larger than the increment at different inflow pressures, thus the value of energy dissipation at different cross sections was large. All these features had relation to pressure difference between ejection fluid and water in the tank at different inflow pressures and sealing process of ejection fluid for nozzle at different sections.