Grain impurity removing, separating and grading system

The invention discloses a grain impurity removing, separating and grading system, and particularly relates to the technical field of grain impurity removing. The grain impurity removing, separating and grading system comprises a separating outer cover and air blowing equipment, the upper portion and the lower portion of the separating outer cover are provided with a feeding port and a dischargingport respectively, the air blowing equipment generates air blowing grains, the output end of the air blowing equipment communicates with an inner cavity of the separating outer cover through a flow dividing pipe, the side, deviating from the air blowing equipment, of the flow dividing pipe is connected with at least two flow collecting plates communicating with the inner cavity of the separating outer cover, and the flow collecting plates are vertically distributed outside the separating outer cover at intervals. In the grain blowing process, a driving device drives the grains to rotate to bounce the grains, in additi