Abstract: According to the reason of one ball eye bing fractured under high load in the power lines, a group of ball-eyes with different metallographic structure were produced by different heat treatment. We detected the metallographic structure in complex shaped ferromagnetic components by contrasting the inductance of the probe above the ball-eyes measured by equipment. We confirmed the capability of the probe to distinguish ball-eyes with different metallographic structure and discussed the influence of the test frequency to the distinguishing ability of the probe. Test results proved it was a simple, feasible and credible testing method to detect the metallographic structure in ball-eyes.