A clip for heat sink comprises an inverted T-shaped retaining member and an L-shaped operation member pivotably connected to the retaining member. The retaining member has a detaining portion defining several openings and a connecting portion extending from the detaining portion. The operation member has a press portion for bearing against the heat sink and a holding portion for being grasped extending from the press portion. The operation member is capable of being driven to rotate from a first position to a second position to cause the detaining portion to interlock with a retention module provided on a printed circuit board, thereby securing the heat sink to an electronic element package on the printed circuit board.