In rotor-bearing system running, vibration signals measured were an kind of Multi-vibration source signals which is overlapping each other. These overlapping signals were difficult to be separated by the ordinary methods, which is adverse to precisely estimate faults of rotor-bearing system in running. In this paper, a test rig was set up to simulate mis-alignment faults; collected vibration signals of bearings were decomposed and reconstructed by algorithm of Mallat. Reconstructed signal can reflect detail character s of bearings vibration. And vibration signals characteristics of fault rotor were effectively identified.