Abstract: Rub-impact of rotor system is a typical failure for an engine.The vibration response of a rub-impacting rotor system exhibits some nonlinear characteristics.How to diagnose the fault of the rub-impact rotor with the new theories of the modern signal analysis has become a noticeable research project.In this paper,the researches of the fault diagnosis of rub-impact rotor are carried out by the theory of nonlinear time series analysis considering the nonlinear dynamical characteristics of the rub-impacting rotor.Based on the theory of phase space reconstruction,the estimations of the embedding delay and dimension are deduced,and the reconstruction of the time series of the rub-impacting rotor system is completed.Then the correlation dimensions of the different time series are estimated.The performances of the diagnosing methods are studied and evaluated by means of the simulation data and the testing data of the rub-impacting rotor.It is found that the correlation dimension values can describe the extent that the behavior of the system approaches to chaos.The different correlation dimension values show the system to be in quasi-periodic vibration,chaotic vibration with quasi-periodic or obvious chaotic vibration.When rub-impact of the rotor system is serious,the correlation dimension increases.The computation of the testing data also prove this.