A heat dissipation device includes a vapor chamber, a heat dissipating fins assembly, a cover and a fan. The vapor chamber is configured to a bent shape. The heat dissipating fins assembly is adhered to a partial surface of the vapor chamber. The cover is connected to the vapor camber. A flow passage is defined between the vapor chamber and the cover. The heat dissipating fins assembly is positioned in the flow passage. The cover defines an opening communicating to the flow passage. The fan is arranged facing to the opening of the cover and other partial surface of the vapor chamber. Therefore, the heat dissipating efficiency can be greatly improved.