The invention relates to an access flap for shielding an opening defined in a server chassis. that the access flap includes a rotating plate, a sliding plate, and a resilient member. The rotating plate is pivotably mounted to a side of the opening of the server chassis. The rotating plate defines a plurality of first air holes therein. The sliding plate is slidably attached to the rotating plate. The sliding plate defines a plurality of second air holes therein. The resilient member includes two ends connected to the rotating plate and the sliding plate. The rotating plate can rotate and the sliding plate can slide when a functional module passes through the opening to enter into the server chassis. Thereby, he second air holes of the sliding plate are aligning with the first air holes of the rotating plate.