A heat sink module has a heat sink, two arms and two fasteners. The arms are slidably mounted respectively in the heat sink to slide along pivotally to move to a certain position on a circuit board. The fasteners respectively extend through the arms and are fastened in the certain position on the circuit board to hold the heat sink on the circuit board. Because the heat sink only needs the arms and the fasteners to be held securely on the circuit board, the manufacturing and assembling procedures are effectively reduced.