The invention discloses a planar phased-array antenna capable of two-dimensional scanning at a wide angle, belonging to the technical field of an antenna. The phase-array antenna unit comprises a dielectric substrate, a radiating patch, a microstrip feed line and a grounding plate, wherein the radiating patch and the microstrip feed line are arranged on the front surface of the substrate, and the grounding plate is arranged on the back surface of the substrate. With a grooving design on the radiating patch, a placing space is provided for a feed network, and the size of the antenna is also reduced; with a coaxial back feeding mode, a signal is divided into two paths to supply equivalent-amplitude same-phase feed to the radiating patch, so that a TM11 mode of the antenna is simulated, the radiation pattern of the antenna has the characteristic of wide beam, and the phased-array antenna has the capability of scanning at the wide angle; meanwhile, in order to achieve a favorable matching effect, the feed network inside the radiating patch is designed in a gradually-changing microstrip mode; and finally, the antenna units are arranged at equal intervals to form an area array structure, the beam coverage angles of the units are relatively large, and the two-dimensional wide-angle beam scanning can be achieved after the units are reasonably arranged.