A performance testing apparatus for a heat pipe includes an immovable portion having a cooling structure defined therein for cooling a heat pipe to be tested. 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 located between the immovable portion and the movable portion for receiving the heat pipe therein. At least a temperature sensor is attached to at least one of the immovable portion and the movable portion for thermally contacting the heat pipe in the receiving structure for detecting temperature of the heat pipe. An enclosure encloses the immovable portion and the movable portion therein and has sidewalls thereof slidably contacting at least one of the immovable portion and the movable portion.