Generally, the flour processed by the flour milling equipment in large milling plants is evenly mixed, but in order to obtain a certain proportion of whole wheat flour, it is necessary to use a small skin-core separation flour mill to obtain flour at different stages. The first stage of milling is crushing milling, that is, crushing wheat to achieve the effect of separating bran from flour; The flour in the second stage is pure flour and whole wheat flour with a small amount of bran; The flour in the third stage is big bran flour, so it is called because the flour in this stage is ground and sieved with a certain amount of bran. At this time, the flour contains a lot of ground bran, which is darker in color and contains a lot of vitamin B2, which is suitable for diabetics. The three kinds of flour can be bagged separately, and the whole wheat flour with different needs can be prepared in proportion when eating.