A novel planar ultra-wideband antenna with double band-notched characteristics was proposed according to the fact that UWB system was easy to be interfered with the narrow-band signals. The new DGS was used on the ground to expand the bandwidth. Two U-shaped slots were utilized on the octagon radiating patch to achieve the double band-notched characteristics within the frequency range of 3.4 to 3.9 GHz and 5.2~5.8 GHz. A pair of branches were used on the fed line to improve the band-notched characteristics. Effects of the two U-shaped slot on the antenna band-notched characteristics were also studied with simulation software. Radiation patterns and gain curves were analyzed, and the proposed antenna was fabricated. Simulated and measured results indicate that the proposed antenna has novel shape, simple structure and good performance. The proposed antenna is also easy to be integrated and can be widely used in UWB wireless communication.