A fan module including a body and a plurality of blades is provided. The body has a rotating axis and the body is telescopic along the rotating axis to have an elongated state and a shortened state. The blades are respectively disposed on the body and rotate along with the body along the rotating axis. At least a portion of each blade is flexible and a bending state of each blade is changed along with the elongated state or the shortened state of the body. An axial size of each blade along the rotating axis when the body is in the elongated state is greater than the axial size of each blade along the rotating axis when the body is in the shortened state.