A new type of steel wire rope non destructive evaluation (NDE) apparatus is presented. It is composed of Hall sensor and signal processing system based on embedded micro processor. The apparatus detects flaws of steel wire rope real-time and on-line. The detection principle, hardware structure and software design of the apparatus are introduced. Examples of the application are given. The experiment results show that quantitatively defect detection of steel wire rope is attained. The apparatus can also be used for the test of the ferromagnetic bars.