Abstract: The structure and basic parameters of propulsion system for existing heavy lift launch vehicles were analyzed.The structure and task requirements were proposed to meet the manned lunar-landing demand.Considering the performance,economics,technical difficulties and working reliability,a scheme of the first stage engine system for heavy lift launch vehicle was proposed,including the thrust level,propellant type and engine cycle.System simulation models were established for 9 model engines using the object-oriented sequential analysis method,and the maximum chamber pressures and balanced system parameters were computed.The influence of chamber pressure and mixture ratio on the engine performance was analyzed.Based on integrative analysis,4 500～5 000 kN liquid oxygen/ kerosene engine system of stage combustion cycle with oxygen-rich preburner is preferred.