The displacement deformation of tailings ponds serves as important early warning indicators for its instability, and accurately identifying plastic displacement is crucial for establishing a safety early warning system for tailings ponds. This study proposes a method for identifying plastic displacement in tailings ponds, systematically analyzes the variation pattern of plastic displacement with applied loads, and establishes the relationship between plastic displacement and the safety factor. The results indicate that the dam body is in the elastic deformation stage during the initial loading period. As the load increases, it enters the plastic deformation stage, and upon reaching the breaking load, the plastic displacement increases sharply. The maximum plastic displacements are 55.986 mm, 49.009 mm, and 44.197 mm, occurring at the sliding arc of the dam body. Furthermore, the safety factor exhibits a nonlinear inverse relationship with plastic displacement: the lower the safety factor, the greater the plastic displacement. Particularly when the safety factor drops below 1, the plastic displacement increases dramatically, indicating imminent dam failure. Based on these findings, the study provides an early identification basis for the instability risk of tailings ponds and proposes a scheme for establishing an effective early warning system, which holds significant engineering application value.