A variable-thrust engine USeS a regulator to control the flowrate and a flowrate posi·
tioned pintle injector to control the injection pressure drop,thus to maintain a stable injection veloc·
ity.In this paper,based on the charaeteritics of the engine system,the main components models are
established and simulated.At the end,the influence of flow resistance in the pipeline upstream the
engine on the engine performance is analyzed.