The space propulsive system is a power system composed of various types of engines.It must be capable of working in space for a long time with very high reliability.When a fault appears

it needs to be detected in time and shut off effectively.In the paper

the authors have introduced a fault reasoning method (fault directional graph) used in space propulsive system

and a corresponding fault reasoning model has been set up.Numerical simulation and theoretical analysis show that the model is simple and effective

and it is possible to be used for space application in a real time way.