Abstract: The present invention relates to an improved fan structure used for a heat sink, and such fan comprises an axle having a first fan member and a second fan member coupled to each end of the axle, and a plurality of leaves arranged in opposite directions are disposed on the first and second fan members such that when the fan is in use, the first fan member is installed onto a heat sink and the second fan member deeply embedded into the heat sink. The hot air conducted to the heat sink is drawn and discharged by the leaves in opposite directions such that the cold air drawn by the leaves of first fan member blows towards the fins of the heat sink to accomplish the convection of the outside cold air and the hot air from the heat sink, which can accelerate the discharge of the hot air.