The lay length is one of the important parameters for the wire rope and its detection can indirectly characterize its stress and surface damage state. The eddy current testing (ECT) method is advantageous because of its easy operation, single-side detection, low requirement of surface preparation, applicability in harsh environment, and other properties. Hence the lay length of the wire ropes is measured by ECT in this paper. The eddy current (EC) response to the wire rope is simulated. The EC on the surface of the strand below the pancake coil forms a vortex, and the distribution of the EC on the curved surfaces on both sides of the strand is symmetrical. The spacing between the adjacent peaks or troughs of the scanning signal is the distance between the adjacent strands, and the number of peaks or troughs of the scanning signal in a range of the lay length is related to the number of strands of the wire rope. Finally, the experimental validation is performed. The relative error of the lay length of the wire rope assessed by the EC method is less than 0.28%.