A heat sink for dissipating heat from an electronic component comprises a heat spreader and a plurality of first fins and second fins provided thereon. The first and second fins are parallel to each other and arranged in alternating order so as to define a plurality of air passages. The first and second fins are so arranged that thinner air passages and denser fin distribution in the middle along the extension direction of the air passages and wider air passages and lower fin distribution density at two ends are provided.