This paper briefly reviews the development history of rotor dynamics, and points out the research objects of rotor dynamics, such as complex rotor systems in turbogenerator, gas turbines, centrifugal/axial compressors and aeroengines, etc. The main research contents involve the dynamics modeling for rotor systems, critical speed and vibration response prediction, the dynamic balancing technology for flexible rotors, dynamic characteristics of bearing, rotor dynamic stability, nonlinear rotor dynamics, rotor fault diagnosis based vibration, vibration control and rotor vibration under multifield coupling excitations, such as electromechanical coupling vibration. Future research mainly focuses on the coupling vibration of rotorstator subsystem, intelligent diagnosis based on big data and vibration control technology considering new materials and structures, etc.