Dynamic Balancing of the Rotor with weakly non-stationary rotational Speed is put forward. After the unbalance vibration signal processed through Time-Frequency Analysis method, the vibration signal information independent of the rotor’s rotational speed, include amplitude value, phase value and Initial Phase Point got in dynamic balance testing. According to the vibration signal information independent of the rotor’s rotational speed, the computation method to get the unbalance mass-radius-product value and phase value through Influence Coefficient Method, Vibration Mode Balancing or Holographic Spectrum Balancing is introduced. Dynamic balancing of the rotor with weakly non-stationary rotational speed doesn’t require the rotor’s rotational speed kept in stationary state. So it eliminates the affection of the non-stationary rotational speed in rotor dynamic balancing and can realize technology of rotor dynamic balancing with ultra p recision.