A clamping mechanism adapted to clamp a heat sink on a housing of an electronic device comprises a frame, a plurality of mounting legs connected on the frame, and a plurality of elastic tabs obliquely extending from the frame towards the heat sink. The frame has a rectangular shape and includes a first arm adapted to be connected to a front end of the housing, a second arm adapted to be connected to a rear end of the housing, and a pair of third arms connected between the first arm and the second arm. The mounting legs are configured to mount the frame on the housing. The elastic tabs press the heat sink against the housing. Each of the third arms has at least one of the elastic tabs.