Abstract: Structural damage identification based on an improved sensitivity technique of structural flexibility is studied in this paper. The drawback of the existing sensitivity methods is discussed firstly and then an improved technique is presented. The most significant contribution of this work is in the development of a simple accelerated formula used in the iteration process. With the introduction of the accelerated formula, the proposed method is able to quantify large damages without any high-order analysis on the flexibility or multi-iterations. The effectiveness of the proposed method is illustrated using simulated data with measurement noise on two numerical examples. The results show that the proposed procedure is economical in computation and is simple to implement. Regardless of whether the damage is small or large, the proposed method can identify both locations and extents of structural damages accurately only using the first iteration. It has been shown that the presented scheme may be useful for structural damage identification.