A heat dissipation device includes a heat conducting plate (100) for contacting with an electronic component (400), a heat sink (200) mounted on the heat conducting plate and a heat pipe (300). The heat conducting plate comprises a groove (110) defined in. The heat pipe comprises an evaporating portion (310) sandwiched between the heat conducting plate and the heat sink, and a condensing portion (320) thermally connecting with the heat sink. The evaporating portion comprises a middle portion (3104) having a circular cross section and accommodated in the groove of the heat conducting plate, and a pair of end portions (3102) formed on opposite sides of the middle portion. The end portions have flat bottom surfaces.