In order to study the dynamic characteristics of the rotor system under unbalanced-misalignment, a dynamic model of the rotor-roller bearing coupling system was established. Consider the parallel misalignment of the gear coupling, and the center of mass and centroid of the rigid turntable are not concentric. Using the Lagrange method, we deduced the dynamic equations of the system. Moreover, numerical analysis is used to analyze the influence of the different misalignment of the coupling, the quality of the different couplings participating in the vibration and the different supporting conditions on the dynamic characteristics of the rotor system. The calculation results show that due to the misalignment, when the rotational speed of the rotor system reaches onehalf of the critical speed, the lateral vibration displacement of the disk increases significantly. That is, the misalignment will make the system at onehalf critical speed. Produce an unstable area. When the rolling bearing is used, as the degree of misalignment increases, the rotational speed corresponding to the maximum amplitude of the rotor in the unstable region gradually increases, and when linear support is used, such a phenomenon has not occurred. As the quality of the coupling participates in the vibration, the vibration of the system at onehalf of the critical speed becomes more and more severely.