The invention discloses a PMU (
Phasor Measurement Unit) 
dynamic data processing method based on feedback iterative frequency tracking. The method comprises the following steps: 1) a frequency value of a measurement 
system is obtained through a difference of a 
phase angle of a current cyclic wave 
phasor and the 
phase angle of a previous cyclic wave 
phasor, and the frequency value serves as the input frequency of a frequency tracking 
processing link after time 
delay correspondence is carried out, so that the tracking compensation correction of a 
system can be regulated immediately along with the change of the real-time frequency of the 
system so as to show high 
measurement precision in a dynamic environment which is changed along with time; and 2) on the basis of a DFT (
Discrete Fourier Transform) 
equalization effect, a time scale of a measurement 
phasor is required to select the window center of a 
processing data window, so that a Lagrange interpolation and 
digital filter of frequency tracking is required as follow: the time scale point is taken as the center, and the processing 
data point numbers of two sides of the time scale point are completely equal. The method is still high in 
measurement precision when a power system is under dynamic conditions including 
frequency drift, amplitude oscillation, phase position oscillation and the like. The reliability of the data measurement and the 
state control of the system under an unstable state can be improved so as to be favorable for the digitized high-precision measurement and control of a 
power grid system to be safe and effective.