The invention discloses a method for identifying the saturation of a current transformer based on the sudden change amount of a sampling value, which comprises the following steps: calculating the secondary side sudden change amount of three phases of each branch according to the collected secondary sampling value of each branch three phases of the bus bar at the current time, and calculating theprimary side sudden change amount of each branch three phases according to the secondary side sudden change amount; According to the absolute value of the primary side mutation of each branch, the maximum value of the primary side mutation of each phase is taken as the maximum value of the primary side mutation, and the sum of the other primary side mutation except the maximum value of the primaryside mutation of each phase is calculated as the sum of the primary side mutation of each phase. Calculate the ratio of the maximum integral of one-time side catastrophe and the sum integral of one-time side catastrophe respectively, and identify the saturation of current transformer according to the ratio of each phase. The invention improves the identification ability of the saturation condition of the current transformer, can judge whether the fault is an in-area fault or an out-area fault, and avoids the malfunction of the protection.