A heat dissipation device includes a main body and at least one heat conduction member. The main body has a top face. A periphery of the top face has a connection section. One end of the heat conduction member is correspondingly in contact and connection with the top face or the connection section. By means of the structure design of the present invention, the horizontal heat dissipation effect is greatly enhanced and the heat dissipation effect of the entire heat dissipation device is greatly enhanced.