A ventilation fan according to the invention comprises a fan module, a fire damper module and a cover module. The fire damper module comprises a link frame, a fire damper body and an adjustment element. The fire damper body is disposed in the link frame and detachably linked up with the link frame. The adjustment element is disposed on the fire damper body and near an opening of a flange of the fire damper body. The adjustment element comprises a fixed portion, a stop portion and a trace portion. Wherein the stop portion abuts and shields the opening when no electrical wire passing through the opening. Wherein when the cover module comprises an electronic device having an electrical wire, the trace portion abuts the opening and the electrical wire passing through the trace portion and the opening to connect to the fan module.