The full flow staged combustion (FFSC) cycle engine balance model was established and the pressure relationship between the fuel-rich flow and the oxygen-rich flow was added in this model.These results show that (1) mixture ratios of preburners are matched for each other

mixture ratio of ox-rich preburner decreases with increasing mixture ratio of fuel-rich preburner

helping to balance the work of two side preburner gases;(2) with the increase of mixture ratio of fuel-rich preburner

the preburner gas temperature is enhanced

the fuel-rich preburner gas mass flowrate is enlarged (the ox-rich preburner gas mass flowrate reduced)

the working ability of preburner gas is reinforced

and the fuel pump lift falls down(the oxidizer pump lift ascends);(3) the mixture ratio of preburner determines the preburner gas temperature

influences the preburner gas properties

participates in the mass flow distribution

controls the working ability of preburner gas

and then affects the pump lift.