A simulation experiment was designed to study subsynchr onous resonance of turbo generator shafts. The Hilbert-Huang transform (HHT) was used to analyze flexural and torsional vibrations of the generator shafts i mpacted by subsynchronous resonance (SSR). The Hilbert spectrum quantitatively d emonstrated the process of flexural and torsional vibrations and showed the ess ential characteristics of the vibration signals. The analysis res ults show that the flexural and torsional vibrations of shafts are interacted wi th each other, and the torsional vibration can suppress the complex shafts motions. Wh en the torsional vibration of the subsynchronous resonance occurs, the torsional vibration frequencies change and the second frequency multiplication disap pear. The Hilbert spectrum of flexural vibration can reflect the frequency variation under the impact, which is helpful to calculation of the torsional vib ration duration.