This paper presents a finite element (FE) model of a dual-disk rotor system with single rub-impact fault and analyzes the effects of different rotating speeds on its dynamic characteristics. The numerical simulations based on the FE model are conducted to study the rotor transverse vibrations of the rotor system. The results are further compared to experimentally measured vibrations. The simulation results show that the motion of the rotor varies from period-one through period-two to period-three with the increasing of the rotating speed; the corresponding frequency components are from multiple frequency components through 1/2 fractional harmonic components to 1/3 fractional harmonic components; and rotor trajectory mainly shows inner concave phenomenon, two nested ellipses and three nested ellipses along rub-impact direction, respectively. In corresponding experimental measurements, combination frequency components including the first natural frequency can be observed besides these features obtained by simulation. These results will provide theory bases for single rub-impact monitoring and diagnosis.