Abstract: A cooling fan, frame structure of the cooling fan, and a heat generating device comprising the fan are provided. The frame structure comprises a body with an air inlet and outlet. The body has at least one set of assembling holes which are spaced a certain distance apart from each other either along the inner peripheral of the outlet or along the two outer opposite edges. The frame structure further comprises at least one active anti-dust baffle with two pins that are disposed in the assembling holes. The active anti-dust baffle is adapted to automatically rotate into a closed position when the cooling fan shuts down to effectively prevent the undesired outside objects from getting into the heat generating device.