Abstract: A band-notched reconfigurable Ultra wideband antenna based on cross slot is designed in this paper. By using 3×3 circular metasurface, the working bandwidth of the antenna is effectively expanded. Through etching two sets of cross slots on the rectangular ground plane and adjusting the on-off state of the eight PIN diodes in the cross slot, the reconfigurable notched band are formed. The proposed antenna can be simply controlled with small size. The results indicate that the antenna can work in the Ultra wideband and band-notched modes. The-10 dB bandwidth of the Ultra wideband mode is 3.5 GHz～8 GHz, covering L-band, S-band and C-band. The band-notched modes include the single band-notched modes at 3.9 GHz, 4.9 GHz and 5.6 GHz, as well as the double band-notched mode at 4.9 GHz and 5.6 GHz. The antenna working in the band-notched modes can effectively suppress the interference from WiMAX and WLAN system.