Civil air defense door convenient to open and close

The civil air defense door convenient to open and close comprises a door plate and a hinge seat, a connecting block is installed on the side face of the door plate, a connecting pin is installed in the middle of the connecting block, the middle of a lower clamping plate and the middle of an upper clamping plate in an inserted mode, and a rolling supporting structure is installed between the lower clamping plate and the connecting block. The door plate can drive the rolling sleeve to rotate simultaneously through the connecting block, the side balls and the lower balls roll relative to the base, opening and closing are labor-saving, the lower ends of the upper balls abut against the upper end face of the connecting block, rolling friction is provided between the connecting block and the upper clamping plate when the door plate is opened and closed, and opening and closing are convenient. When the door plate needs to be temporarily fixed, the elastic piece can be rotated upwards, the rubber pad is tightly attac