Through analyzing various principles of single-phase grounding fault selection in small current grounding power systems，a new method of single-phase grounding fault location based on a distribution automation system is presented， in which a logical space model and an information fusion algorithm are built with the information resources of the distribution automation system. The fusion algorithm synthetically considers electrical characteristics of each node of power networks and their distribution rules in the network topology， and takes the contribution of logic“0” into account as that of logic“1”. Furthermore， the validity of the algorithm is deduced theoretically and an evaluation index for the fault-tolerant ability is derived. The adaptability and fault-tolerant ability of the proposed method proves to be favorable by an application example subsequent to the theoretical analysis and index evaluation.