A method for sealing a heat pipe, includes the steps of: providing a metallic pipe with an end sealed and an opposite open portion; pressing the open portion of the pipe to form a two layer portion by using two pairs of pressing molds; welding an end part of the two layer portion to form a sealing structure, during which at least one pair of pressing molds continues pressing the two layer portion; and moving the at least one pair of pressing molds away from the sealing structure.