A heat pipe includes a metal casing (100) and a composite capillary wick received in the casing. The casing has an evaporating section (400), a condensing section (600) and a central section (500) between the evaporating section and the condensing section. A first type of capillary wick (250) is provided in the central section of casing and a second type of capillary wick (240) is disposed at the evaporating section of the casing. The capillary pore size of the first type of capillary wick is larger than that of the second type of capillary wick and the first type of capillary wick is made by stacked metal sheets.