Fastening device for heat sink

This invention relates to a locking device of heat sink used in fixing a heat sink on a CB and including: a body, a first locking piece set on one end of the body, a second locking piece set on the other end of the body and an operating piece connected with the first locking piece, in which, said operation piece includes a cam part pivoted with the first locking piece and the rotation of which candrive the cam part to lean against a bearing side of one end of the body to drive the first locking piece to move upward relatively to the body, a spacing structure is formed on the cam to lean against the first locking piece.