Wheat samples were obtained online at the import and export of gravity grading stoner from two wheat flour production lines and were milled into wheat flour by experimental grinder. The results showed that: after gravity classification the content of full grain in the group of heavy wheat increased, the flour processing accuracy was enhanced, the quality characteristics was improved; although there was a slight decline in the content of glutenin and gliadin, the gluten index increased, the formation time and stability time of the dough extended, falling number and peak viscosity, low viscosity and final viscosity all had different degrees of increase. The flour yield and flour processing precision of light wheat were reduced and quality characteristics degenerated; the more the light wheat contained the grain that was not full, the more significant the difference.