In order to solve the problem of surveying the magnetic head's lubricating thickness repeatedly in the production process, the dynamic tests were done repeatedly by using Atomic Force Microscope (AFM) . The results have shown that, below 25 angstroms, where the head reads and writes data, were carried out the relationship between the lubricant thickness and the distance of the point from the disk center is linear. From 25 angstroms to the edge of the disk, by using the improved Euler method to process the data, the relationship between the difference of the calculated value and the actual value was found, and the distance of the point from the disk center is linear.The theoretical analysis and actual confirmation of the experiment errors were carried out, with indicated that, because of the air current pressure release and the partial magnetism releases caused by the magnetic head gap in the diskette edge, the magnetic head edge lubricating thickness is very difficult to forecast.