Abstract: In an operational hard disk drive (HDD), a slider is flying over a rotational disk and the dynamical flying characteristics of the slider have important effects on the performance of the HDD. By using the perturbation method, the perturbation equations for the gas film stiffness and gas film damping of the slider are derived, and the perturbation equations are numerically solved by the finite volume method (FVM). The gas film stiffness matrix and gas film damping matrix are obtained with an initial perturbation condition. Based on the dynamical equation of the slider, the effects of disturbance velocities, disturbance pitch angles and disturbance roll angles on the dynamical flying characteristics of the slider, are studied. The study results show that the perturbation velocities can cause the slider to move toward the disk, which increases the collision risk of the slider with the disk. The increases of disturbance pitch angles and disturbance roll angles will increase the vibration amplitudes of the flying parameters for the slider, and the disturbance angles are more likely to cause the vibration of the slider.