A fan includes a frame, a first impeller, a motor, a base, and a noise silencer. The frame is provided with a flow channel for air to flow through. The first impeller is disposed in the frame. The motor connects with and drives the first impeller to rotate. The base is disposed in the frame and supports the motor. The noise silencer is located adjacent to the flow channel. The noise silencer includes at least one hollow chamber, and the hollow chamber has at least one hole communicating with the flow channel.