Addressing the challenges associated with complex detection methods and the difficulties in ensuring accuracy when measuring key dimensions such as the axial length and chord length of magnetic tiles, this study proposes a sub-pixel magnetic tile edge detection method that enhances the traditional LoG-Zernike moment approach. Initially, the collected images undergo preprocessing, followed by the application of adaptive median filtering to optimize the conventional LoG operator, thereby achieving pixel-level coarse positioning through filtering and denoising. Subsequently, the Zernike template is employed to calculate the edge threshold, with the optimal step threshold determined using the two-dimensional Otsu algorithm to identify the sub-pixel points along the edge. Finally, the least squares method is utilized to fit the edge of the magnetic tile. Experimental results indicate that the relative error rates for the magnetic tile shaft length and chord length are 0.060% and 0.018%, The precision of the errors is kept within ±0.01 mm and ±0.004 mm, respectively, while the average time taken for detection per magnetic tile is 1.56 seconds.The effectiveness and practicality of the method have been confirmed.