Rotor displacement signal is an important parameter of rotating machinery condition, which contains abundant operation condition information of rotating machinery. The basic method and principle of harmonic wavelet packet algorithm were briefly introduced.The harmonic wavelet algorithm was used to purify the rotor displacement signals in the process of speed rising of the largescale sliding bearing test rig, to extract the characteristic frequency of purified signals and synthesize rotor orbit. Combined with the structure of the test rig, the reason of the orbit shape was analyzed under various conditions. Finally, by extracting the DC component of each signal at different speeds, the uplift process of the rotor was shown visually. The feasibility of the harmonic wavelet to purify the rotor orbit and the correctness of operation condition analysis of test rig were verified.