To study the system fault evolution process, and mine the relationships among the fault data, fault factors and fault events, we propose the theory of space fault network. The paper is composed of three parts. In the first part, the shortcomings of the existing studies on unidirectional ring in space fault network are discussed, and three new network description forms of typical unidirectional rings are formulated and the corresponding space fault tree transformation mechanism. The concepts of ring structure, ordered relation, equivalence event and equivalence connection are defined according to the need. Three methods for calculating the target event probability are given. The second part studies the all event induction fault evolution process. All of its edge events and process events lead to the target event. The meaning of all event induction fault evolution process is discussed. Two methods, general fault evolution process and all event induction fault evolution process, are used to calculate the target event probability in the evolution process of a single route and network structure. In the third part, the impact of some event repeatability on the fault and the time characteristics of the evolution process are studied, and the definitions of event repeatability and timeliness are proposed. The occurrence time and duration of events and connections are given to characterize the time characteristics. Finally, according to repeatability and timeliness, the measures to prevent the target event are given. The paper provides a new theory and method for mining system fault evolution process from fault data, fault factors and fault events. INDEX TERMS Safety system engineering, space fault network, unidirectional ring structure, all event induction, repeatability and timeliness, fault data mining.