Abstract: Some simple dynamic balance methods of rotor systems are investigated These methods featuring simplicity and ease without recourse to any complicated instrumentation and calculation system are particularly suitable for rotor balance in field. The simple rotor balance method with influence coefficients and that with least quadratic are presented. The balance problems of rotors with non-axisymmetrical support stiffness and for rigid rotor systems in field are also discussed. Some practical examples prove the methods presented are applicable.