Abstract: According to the principle of energy, a potential energy equation for tensile type anchors is established based on the ideal elastoplastic soil model. Under the constraints of the minimum potential energy, the analytical solution about the relationship between drawing load and anchoring body length is derived, the ultimate anchorage length is proved, and the values of the anchorage length under different soil environments and their impact factors are found. By introducing the fuzzy theory, a fuzzy identification model is proposed to judge failure state of anchors using the energy method. The failure membership function and the critical fuzzy interval in the model are analysed. By comparing the proposed method with the actual project, the results show that the proposed model is feasible and effective. The energy method-based fuzzy identification can be used to analyze the reliability of anchor reasonably. Most of the damage cases of anchors can be explained.