The invention provides a method for quickly positioning the oscillating center of an electric system. In application aspects of inhibiting the oscillation of the system, coordinating the disconnection and the like, the accurate position of the oscillating center of the electric system often needs to be known. By the method, only the electric quantity and natural parameters of circuits need to be measured on the spot, the out-of-step oscillating center of the system can be accurately judged at the synchronous oscillation stage of the system, and the out-of-step quick disconnection criterion isrealized based on the on-the-spot electric quantity. By the popularization and the application of the method for positioning the oscillating center based on the on-the-spot electric quantity, and thecombination of the reliable quick disconnection criterion, the out-of-step disconnection control can be realized quickly, reliably and on the spot, and the method can also be adapted to different operating modes of the system, and realize the coordinating control of a plurality of disconnection devices.