A performance testing apparatus for a heat pipe includes an immovable portion having a cooling structure defined therein for cooling the heat pipe. A movable portion is capable of moving relative to the immovable portion and has a cooling structure defined therein for cooling the heat pipe. A receiving structure is defined between the immovable portion and the movable portion for receiving the heat pipe therein. A concavo-convex cooperating structure is defined in the immovable portion and the movable portion to ensure the receiving structure being capable of precisely receiving the heat pipe. Temperature sensors are attached to the immovable portion and the movable portion to detect a temperature of the heat pipe. An enclosure encloses the immovable portion and the movable portions therein, and defines a space for movement of the movable portion relative to the immovable portion.