Compared to traditional two-dimensional frequency selective surfaces, three-dimensional frequency selective surface has become a hot research direction due to its ability to generate more resonance points, provide larger bandwidth, efficiently meet miniaturization requirement, and bring more stable frequency response. A novel three-dimensional frequency selective surface with a multi-level orthogonal diamond structure is proposed in this paper. Its basic unit structure is an orthogonal diamond-shaped metal wire, and a polymer with dielectric constant of 2.2 is injected externally as support structure. The common bandwidth of this frequency selective surface exceeds 9.2 GHz with a relative bandwidth exceeding 50%, and the average insertion loss of TE and TM polarization does not exceed 1 dB when the incident angle in the range of 0° to 50°. This three-dimensional frequency selective surface has three resonance points. Their formation reasons are the resonance of the orthogonal diamond metal structure, the resonance generated by the coupling between the structure and the dielectric end face, and the first-order Fabry Perot resonance of the dielectric end face. If the dielectric constant of the filling medium is adjusted, higher order of Fabry Perot resonance can be utilized, and a spatial filter with broader bandwidth requirement can be designed. At the same time, the impact of this three-dimensional frequency selective surface on the far-field pattern of the antenna is also evaluated.