The invention provides a circularly polarized F-P resonant cavity antenna with high gain and low RCS, and aims to simplify the structure of the antenna and reduce the manufacturing cost of the antenna. The antenna comprises an upper dielectric plate and a lower dielectric plate, a wave-absorbing surface is printed on the upper surface of the upper dielectric plate, a partial reflection surface isprinted on the lower surface, the wave-absorbing surface comprises N*N wave-absorbing units arranged in a periodic manner, the wave-absorbing units adopt annular patch structures, four edges of the wave-absorbing units are provided with gaps, resistances are loaded on the gaps, the partial reflection surface comprises N*N partial reflection surface units arranged in a periodic manner, the partialreflection surface units adopt square patch structures, the center of each partial reflection surface unit is provided with a cross slot with different length and width, four edges of the partial reflection surface unit are provided with rectangular grooves, a rectangular metal patch is printed on the upper surface of the lower dielectric plate, a floor is printed on the lower surface, the rectangular metal patch and the floor are connected through a coaxial line, and a high-impedance surface formed by an area array formed by periodic arrangement of a plurality of strip-shaped metal patches isprinted around the rectangular patch.