Abstract: Abstract The standard SEP 1572—2019 was used to evaluate the sulfide inclusions in free cutting steel. The comparison method and imaging instrument method in the standard were introduced, and the differences between the new version of standard SEP 1572—2019 and the old version of standard SEP 1572—1971 were analyzed. The results show that using the comparative method to evaluate inclusions was relatively simple and fast, but the results were susceptible to human interference. The results of inclusion evaluation by image instrument method were more accurate. In the new version of the standard, the standard map of comparative method was a simulated map, and the number of maps was increased from 12 to 26, with both row and column values increased.