Relay logic diagram analysis is the core function of graphic-oriented programming software. There are many feedback loops in relay logic diagram. Topological sort can’t be applied to relay logic diagram analysis directly because of the feedback loops. Now, most of graphic-oriented programming softwares solve the problem by manual intervention. Aiming at the problem, this paper delves into the topology analysis based on activity on vertex directed diagram (AOV) networks and proposes the directed loop diagram analysis algorithm based on feedback component. This algorithm achieves looping-off automatically and solves the difficulties of analysis and processing of the loop diagram. The mechanism has the characteristics of easy implementation, better generalization and high reliability, and is adopted in the relay-protection development.