In the paper, a tri-band angularly stable frequency selective surface (FSS) with controllable resonances for electromagnetic shielding is proposed. Different from traditional single-layer structure, the FSS proposed is based on cascaded structure that creates three adjustable blocking bands around frequency 5.93 GHz, 7.33 GHz and 9.17 GHz, respectively. The designed FSS has a low profile with thickness of λ 0 /100, where the λ 0 represents wavelength of the first band-stop resonance frequency. Besides, the proposed FSS exhibits stable frequency response up to 70° with respect to different polarizations. Therefore, this FSS is flexible and can be used in electromagnetic shielding field where needs conformal screen. To investigate and understand the operating mechanism better, a equivalent circuit model (ECM) is deduced and given in the Section 2, the calculated results match the full-wave EM simulation results perfectly. Finally, a prototype of this FSS is fabricated and measured, the measurement results are in accordance with the simulation results.