The invention discloses a round electrical connector, which comprises a socket, a plug and a tail clamp, wherein the plug can be plugged at one end of the socket; the tail clamp can be connected to the other end of the socket; the round electrical connector is characterized by comprising a socket shell, a jack assembly, a rotating ring, an expansion block and a pressing ring; the jack assembly is arranged in the socket shell; the rotating ring is rotationally connected to the outer wall of the socket shell; the expansion block is connected to the socket shell in a sliding manner; the pressing ring is movably connected to the socket shell; the rotating ring and the expansion block are in linkage cooperation, so as to achieve rotation of the expansion block along the rotating ring and to carry out a telescopic movement along the radial direction of the electrical connector; the plug comprises a plug shell and a contact pin assembly; the contact pin assembly is arranged in the plug shell and is butt-jointed to the jack assembly; a clamping groove is formed in the plug shell and is matched with the expansion block, so as to achieve plugging of the plug and the socket; the tail clamp can be clamped on the socket; and the pressing ring can contact the tail clamp, so that the tail clamp cannot be arranged on the socket any more; and the tail clamp is separated from the socket