By using modal filtering method, a modified sensor fault detection approach based on structural dynamic characteristics is presented. An array of accelerometers attached on the surface of the beam are taken as sensors. The differences between the reconstructed signals by modal filtering and the measurement signals are obtained, then the curvature of the errors are taken as sensitive index to detect and identify the simulated fault sensor of sensor array. The numerical simulation and experimental result show that the proposed method can detect the fault sensor efficiently. Furthermore, this method is independent of the location of the excitation and it can be used for real-time monitoring system.