Disclosed is an automatic-adaptation under-frequency load shedding method based on a frequency changing rate response. The method comprises the steps of (1) measuring frequencies (Fg and Fj) of electric generators inside a region, rotational inertias (Mg and Mj) of the electric generators and active powers (Pl and Pi) of load nodes, and setting first-time control parameters; (2) calculating the center of inertia frequency Fcoi of a system inside the region and the total active power Pl inside the region through a control center; (3) monitoring changes of the Fg and Fj of the electric generators inside the region through the control center, and if the Fcoi is continuously lower than a first-time load shedding frequency threshold value Fset and the time when the Fcoi is continuously longer than a first-time load shedding time threshold value Tset, executing the step (4), or executing the step (3); (4) shedding Pshed,1% loads; (5) recording the time when the step (4) is completed as Tshed, and determining times t1 and t2; (6) calculating a system initial active power shortage delta Pt=t0; (7) determining a second-time load shedding proportion Pshed,2; (8) transmitting the Pshed,2 to the load nodes inside the region from the control center, and shedding Pshed,2% loads. The automatic-adaptation under-frequency load shedding method can automatically adapt to changes of system inertias, load characteristics and active power shortage, and after the automatic-adaptation under-frequency load shedding method is adopted, the system frequency restoration effect is better compared with a round-by-round under-frequency load shedding method and a semi-automatic adaptation under-frequency load shedding method.