A postprocessing procedure is presented to suppress spectral shadowing in phase-OTDR sensing systems based on a weak fiber Bragg grating array. A complete theoretical analysis of the interfering signals has been carried out to identify a compensation method. The proposed approach has been applied to simulated and experimental phase-OTDR in the context of vibration measurements. Fast Fourier transform has been employed to analyze the obtained results, which has verified the validity of the proposed method to suppress spectral shadowing.