An assembling structure of heat dissipation device includes at least one heat pipe, a first and a second radiating fin assembly. The heat pipe has a heat absorption section, at least one heat releasing section and a curved section between the heat absorption section and the heat releasing section. The heat releasing section is fitted in multiple perforations of the second radiating fin assembly. The curved section is fitted in multiple notches of the first radiating fin assembly. Each notch is defined with an open side and a closed side. The closed side extends along a curved outer side of the curved section and contacts and attaches to the curved outer side of the curved section. Accordingly, the utility ratio of the heat pipe is increased. Also, the heat dissipation area of the heat pipe is increased and the heat dissipation efficiency of the heat dissipation device is enhanced.
