A simple and compact ultra-wideband CPW-fed printed monopole antenna with dual band-notched performance is presented in this paper. The proposed antenna has the bandwidth from 3.01 GHz to over 12 GHz with dual stop bands at 3.5 GHz WiMax and 5.8 GHz WLAN which are achieved by a simple circular slot and a compact coplanar waveguide resonant cell respectively. The geometry parameters of the antenna are investigated and optimized with HFSS. A quasi-omnidirectional and symmetrical radiation pattern in the whole band is also obtained. As a result, this kind of band-notched UWB antenna requires no external filters and can be applied in the UWB communication systems with the anti-jamming ability or low interference ability to other wireless systems.