The present invention relates to a heat sink assembly structure having at least a heat sink fastening member combined with at least a heat sink. Each heat sink fastening member has a V-shaped protrusion, a slot, and an elastic lock member. The elastic lock member has a V-shaped cross sectional structure. The V-shaped protrusion of a first heat sink is combined tightly in the slot of a second heat sink for assembling the heat sink and for forming a V-shaped slot. The assembled heat sink is fixed in a base by adding a solder into the V-shaped slot.