A phased-array antenna and a method for controlling the same are provided. The phased-array antenna includes first and second substrates between which a cavity is formed. Phase-shifting units in the cavity each includes: a power feeder located on a surface of the first substrate facing away from the second substrate and connected to a radio-frequency signal terminal, a radiator located on the surface and insulated from the power feeder, a ground electrode located on a surface of the first substrate facing towards the second substrate. The ground electrode connects to the ground signal terminal and overlaps with the power feeder and the radiator and includes a first and a second openings. A transmission electrode located on a surface of the second substrate facing the first substrate and connects to the control signal line.