A water-cooling heat dissipation device includes a vapor chamber, a heat conduction cylinder, and a cover. A first chamber is formed in the vapor chamber. The heat conduction cylinder extends from a surface of the vapor chamber. A second chamber communicating with the first chamber is formed in the heat conduction cylinder. A working fluid flows in the first chamber and the second chamber. The cover covers the vapor chamber; the heat conduction cylinder is disposed in the cover. By means of the working fluid flowing in the first chamber and the second chamber which communicate with each other, heat can be delivered rapidly from the vapor chamber to the heat conduction cylinder.