The invention relates to a differential protection method and apparatus, and a CT saturation identification method and apparatus, and belongs to the technical field of relay protection of a power system. An original differential current is subjected to differential calculation firstly; whether sampling point distortion occurs or not is determined based on a ratio relation between an absolute value of each sampling point and an absolute value of the largest sampling point in one sampling cyclic wave; and if the number of distortion points is greater than a first set number of sampling points, CT saturation is determined; then the number of the sampling points which satisfy the ratio of the original differential current to the original braking current is calculated; and whether the number of the sampling points satisfies the number of the sampling points of the set ratio is determined, and differential protection is started. Correct determination on the differential current sampling points with intervals for single-power intra-region saturation is realized. By adoption of the method provided by the invention, the CT saturation types can be rapidly identified, so that the differential protection can be closed or opened correspondingly, and the reliability of the differential protection action is improved.