Aiming at the problems of low-frequency coverage, angle and polarization instability of ultra-wideband (UWB) frequency selective surface (FSS) in practical application, this paper introduces the additional circular parasitic patches and two-stage rectangular bent grids to enhance coupling, miniaturize geometry size, broaden bandwidth and suppress the drift of resonance frequencies based on the construction of a FSS unit cell by using a basic circular patch and a Jerusalem cross grid. The simulated and measured results show that the bandwidth of the FSS is 13.47 GHz, and its fractional bandwidth is 140.53%, which fully covers the UWB band (3.1–10.6 GHz). The UWB FSS has the flat transmission passband, and high transmission characteristics, and maintains stable performance at large incident angles and different polarization modes. The size of the UWB FSS unit cell is 0.25 λc × 0.25 λc × 0.12 λc. Therefore, the UWB FSS can be applied to electromagnetic stealth and the related fields of UWB communications.