For crack defects near the surface of metal components, based on the far-field eddy current detection method, a far-field eddy current detection sweeping system that includes a motion sweeping platform, signal excitation, data acquisition and other modules is established. The motion sweep platform uses PLC to control the stepping motor to drive the three-dimensional sweep frame movement. A LabVIEW data acquisition program was written to control the NI acquisition card to collect the detection signal, and MX components were used to communicate between the LabVIEW software and PLC so that LabVIEW could access the PLC's registers to read the three-dimensional sweep frame displacement information of each axis. Automated detection of defects was achieved by combining software and hardware. Two different types of defects were designed. The experimental results show that with decreasing defect depth and increasing defect width, the obtained defect signal also increases, and the error between the actual defect position and the detected defect position is 0.001 mm; at the same time, the method is able to detect rectangular defects with a maximum depth of 5 mm and width of 0.2 mm, which proves the feasibility of the method.