In this work, a broadband frequency selective surface (FSS), which is insensitive to incident angle is designed. This FSS is composed of three metallic layers and two identical dielectric layers. The top and bottom layers are two identical metal patches, while the middle layer is a slot structure etched in a metal screen. This FSS achieves a broadband pass‐band response from 9.8 to 20.8 GHz by combining different resonant modes at 12.6, 15.2, and 19.2 GHz, respectively. Meanwhile, this FSS can still function properly at up to 60° oblique incidence for TE polarization, which is attributed to the independence of incident angle of the middle slot layer and miniaturization of the whole structure. In addition, two key parameters (that are of great importance in adjusting flatness of the pass‐band) of the FSS element have been studied. A prototype of the FSS was manufactured and measured. Good agreements between measurements and simulations are observed.