An exemplary flat heat pipe includes a cover, a wick structure adhered to part of an inner surface of the cover and working medium contained in the wick structure. The cover defines a receiving chamber therein. The wick structure is received in the receiving chamber and includes an interface surface away from the inner surface of the cover. The interface of the wick structure and the exposed inner surface of the cover cooperatively define a vapor passage therebetween. Vaporized working medium enters the vapor passage only from the interface
