A heat pipe includes a casing (100) containing a working fluid therein and a capillary wick (200) arranged on an inner wall of the casing. The casing includes an evaporating section (400) at one end thereof and a condensing section (600) at an opposite end thereof, and a central section (500) located between the evaporating section and the condensing section. The thickness of the capillary wick formed at the evaporating section is smaller than that of the capillary wick formed at the central section in a radial direction of the casing. The capillary wick is capable of reducing thermal resistance between the working fluid and the casing.