Abstract: Based on structural modal test theory and finite element method, strain sensitivity ratio method of detection for the corrosion damage in pressure pipeline is presented. First, the damage-locatization criterions to locate damage through displacement mode and strain mode are established. Secondly, all kinds of pipelines with different damages are prepared and detected by this damage detection method. The result shows that the damage location predicted by this method is the same as the real one. Finally, the numerical example verifies that the result using the first one-order modal shape is basically consistent with the real damage. These results prove that strain sensitivity ratio method locating damage in pressure pipe only require measurements of few of the pipeline’s natural frequencies and the lower displacement mode under both the undamaged and damaged states. And this method is shown to provide good predictions of damage location. Since the lower-order modal shape can be measured easily, this method is convenient to apply in engineering practice.