The invention discloses an octagonal flat-type array antenna comprising an earth plate and a circularly-polarized four-point feeding network, wherein the earth plate is provided with a central radiating element assembly and two groups of coupling plates arranged by equal distance along the radial direction. The octagonal flat-type array antenna can receive signals transmitted by a plurality of navigation and positioning satellite constellations and meet the requirement for high-precision carrier phase measurement. A high-precision receiver antenna for GNSS (Global Navigation Satellite System) carrier phase measurement can be provided for users of ocean, land, air and space, and the octagonal flat-type array antenna can also be popularized and applied to a radio transmitting and receiving system with a stable radiating phase center and a circular polarization and hemisphere beam coverage requirement. The octagonal flat-type array antenna has the characteristics of stable radiating phase center, circular symmetry of radiation pattern, high roll-off, high front-to-back ratio and favorable wide angle circular polarization, has favorable anti-multipath and broadband operation capacity and is a novel GNSS high-precision carrier phase measurement type user compatible receiver antenna.