A low-profile broadband circularly-polarized array antenna based on stacked traveling wave antenna elements, includes: a circularly-polarized antenna element composed of three segments connected in an end-to-end manner of metal layers printed on two sides of a dielectric slab and a metallized via connecting two layers; a 2×2 antenna sub-array composed of a metallized via cavity and four antenna elements; a 16-way full-parallel feeding network composed of the metallized vias; slots for coupled feeding between feeding layers and metal cavities and the antenna; and a switching structure for testing between a grounded coplanar waveguide (GCPW) and a substrate integrated waveguide (SIW). An antenna array designed can be manufactured by using a printed circuit board process. The antenna array can realize circularly polarized radiation in a very broad frequency band.