A heat pipe includes a hollow metal casing (100) and a honeycombed wick structure (200) arranged at an inner surface of the hollow metal casing. The wick structure includes a plurality of slices (210, 220) stacked together. Each of the slices has a plurality of pores therein and a plurality of protrusions (222) formed thereon along a longitudinal direction of the heat pipe to form a plurality of liquid channels (230) in the wick structure along the longitudinal direction of the heat pipe. Each liquid channel has alternate large and small sections (232, 231) along a length thereof.