The invention discloses a movable drum door. The movable drum door comprises two rails, two adjustment screws, a drum door body, a support and idler wheels. The movable drum door is characterized in that fixed seats are evenly distributed on the rails; stand columns, fixed screws and turning screws are arranged on a drum body, and the stand columns and the fixed seats are locked together through nuts; the two rails form a rectangle through the two adjustment screws, and the fixed screws and the turning screws are in locked seal with the drum door body through handle nuts; a drum door screw is arranged on the drum door body and integrally connected with the support; idler wheel carriers are arranged on the support, and the idler wheels are arranged on the idler wheel carriers in a combined mode through hinge pins; and the idler wheels roll on the rails to drive the support and the drum door body to move together. The movable drum door is simple in structure, convenient to operate and good in airtightness; the drum door body is automatically separated from a drum opening of the drum body after the handle nuts are loosened, and the drum door body can move to one side; and the movable drum door is suitable for various rotary drums.