In order to reflect the status of relay protection device more scientifically, reasonably and objectively, a state evaluation method of relay protection based on fuzzy DEA theory is proposed. Based on the consideration of the effectiveness and feasibility, combined with the fault condition of relay protection, this paper extracts state monitoring information, and associates with the historical operation information and other factors, then establishes the evaluation system of relay protection. Concepts such as the theory of fuzzy evaluation set and fuzzy Gaussian membership functions are introduced to quantify the qualitative indicators. Then the improved fuzzy DEA model based on the cut set solution is used to evaluate the running state of relay protection device, and running state evaluation results are got by average efficiency value. Finally, the validity and rationality of the method are verified by an example.