Since traditional low strain reflected wave method is essentially empirical, a misleading estimation of the damage location of pile foundations may be made. To address this issue, an improved method based on the change of phase angle is presented to detect the position where effects occur. Firstly, the analytical modal decomposition and recursive Hilbert transform are combined to extract the FM parts in a specific region of interest. Secondly, continues wavelet transform is performed on the extracted FM parts to acquire the phase angle and thus the damage is identified according to the varying of the phase angle. Finally, the measured data of the pile of Wangqian #1 Bridge is used to verify the effectiveness and accuracy of the proposed method, and the results demonstrate that the proposed method can preliminarily detect the damage location of the pile and thus facilitate the following damage confirmation, but it still needs more extra proofs based on other damage detection methods or engineering data.