Abstract: The national standard of non-metallic inclusion inspection will be revised soon. In order to improve the standard, the GB/T 10561—2005 Steel—Determination of content of nonmetallic inclusions—Micrographic method using standard diagrams was studied in detail, and compared with the old national standard and corresponding international standards. The results show that GB/T 10561—2005 is more perfect than the old version of GB/T 10561—1989. It stipulates that the inclusion should be graded according to the length, thickness, diameter, particle number and distribution of inclusions, which is convenient for the test personnel to operate and is conducive to the accurate evaluation of steel quality. GB/T 10561—2005 needs to be further improved in the aspects of text editing, principle formula, actual inspection rules, result expression and atlas making.