A the wick structure of a heat pipe includes a woven mesh curled to be located inside a tubular member of the heat pipe, and a plurality of fiber bundles longitudinal attached to an interior surface of the tubular member and sandwiched between the woven mesh and the tubular member. The fiber bundle provides capillary action in the longitudinal direction, and the woven mesh provides capillary action in the longitudinal direction, as well as in the transversal direction. Therefore, the wick structure can provide capillary action in both the longitudinal and transversal directions.