A heat pipe includes a metal casing (100) filled with a working fluid therein, a capillary wick (200) provided inside of the metal casing and a tube (300) contacting with a surface of the capillary wick. The capillary wick extends in an axial direction of the casing and has a middle portion separated from an inner wall of the metal casing. A vapor passage (700) is formed between an outer wall of the tube and the inner wall of the casing and a liquid channel (800) is defined by the capillary wick. The working fluid in vapor state flows along the vapor passage and the working fluid in liquid flows along the liquid channel. The tube separates the vapor from the liquid at a place where the tube is located.