The invention discloses a stepped sealing type bin door, and belongs to the field of fodder machines. A swing arm is driven by a cylinder to rotate, two semicircular bin door bodies arranged on a rotating shaft can overturn or be laid flat, the unloading and material sealing effects are achieved, and therefore the purpose of sealing powdery materials which are prone to flowing is achieved. The stepped sealing type bin door is characterized in that the two semicircular bin door bodies are arranged on the rotating shaft in a high-low staggered manner to form a stepped turning plate; sealing strips are arranged on the inner wall of a bin door cylinder in a vertical staggered mode and overlap a turning plate shaft; materials can not flow down from seams in the two ends of the turning plate shaft; when the turning plate is laid flat, the stepped turning plate makes close contact with the sealing strips so that the materials can be sealed; and when the turning plate is driven by the cylinder to rotate by a certain angle, the sealed materials can be rapidly discharged. Compared with the prior art, the stepped sealing type bin door has the beneficial effects that the bin door is good in sealing, the bin door is circular, diameter changes are not needed when the bin door is connected with a circular weighing bucket, and the height of devices can be reduced so that cost can be saved.