This disclosure relates to the field of communication device technologies, and provide a phase shifter, an antenna, and a communication base station, to resolve problems of a high transmission loss and a large size of the phase shifter. The phase shifter includes a carrier board, a metal housing, a fastening medium, a sliding medium, and a metal feed plate. The carrier board includes a first metal layer disposed on one side. The metal housing is mounted on and fastened to a surface of the first metal layer, and is electrically connected to the first metal layer. The fastening medium is fastened and mounted in the metal housing, the metal housing and the fastening medium enclose a sliding cavity, and a relative permittivity of the fastening medium is greater than 1.