Abstract: A structure for expanding thermal conducting performance of a heat sink includes a bottom plate, a top plate, a hollow filling tube, a wick structure and a hollow thermal expansion conductor. The top and bottom plates are covered with each other to form a planar shell, in which an upper receiving chamber and a lower receiving chamber are formed. The wick structure is attached to the planar shell in upper and lower receiving chambers. The filling tube is filled with a working fluid. The thermal conductor has good conducting performance and is embedded in the planar shell. Further, the thermal conductor is in fluid communication with the upper and the lower chamber, such that the thermal conductor can serve as an extension of the planar shell for heat dissipation.