At present, the theoretical explanation of wheat hardness in the grain chemistry community is: the hardness is determined by the bonding strength between the white paper matrix and starch in the endosperm cells, and this bonding strength is controlled by genetics. In hard wheat, the protein and starch are tightly bound, and the cell content is firmly bound. When the wheat flour is machined, the damage first occurs in the cell wall, not through the cell content. When continuing to study the cells, some starch grains were passed through the damaged area instead of at the interface between starch and protein. The starch and protein contained in the endosperm cells of soft wheat are similar in appearance to those of hard wheat, but the surface of the starch grains of soft wheat has more protein with a molecular mass of 15K atomic mass units. There is little or no protein content on the surface of starch granules. The presence of starch granule protein physically weakens the bonding strength between protein and starch. Because the combination between protein and starch is not strong and easy to break, the grains can be crushed with less force, and there are few damaged starch grains.