Inlet pressure of the liquid rocket engine should be controlled in a range by the
propellant supplying system in the ground test．At present，the pressure is controlled by an electromagnetic
valve which is driven by a pressure relay．But the regulation precision is low and the response
hysteresis is significant．A new project is put forward in this paper which is based on the ex—
pert control system and the experience of the open-loop control system during these years，the exec·
utive is a series of valves．The virtue of the new project is that it does not need precision mathmatic
model and the pressure will follow the set value well after controlling of the valve matrix in the design
precision．