The invention discloses a remote upgrading method of concentrators. The remote upgrading method mainly comprises the following steps: (1) the concentrators required to be upgraded are grouped according to manufacturers of the concentrators and the currently operated program version; (2) upgrading initialization is carried out on the concentrators; (3) a master station transmits upgrading firmware to the concentrators in groups by a multicasting manner; (4) the master station transmits lost firmware blocks in multicasting transmission to the concentrators by a point-to-point way; (5) the concentrators activate the firmware according to a firmware activation way in an initialization command; (6) the concentrators perform pilot run on new firmware within safe time; (7) the new firmware is selected to be formally operated or the firmware is regressed according to pilot run results of the new firmware by the concentrators. By adopting the method disclosed by the invention, a master station system can carry out remote upgrading on the concentrators quickly, controllably and safely to lower the upgrading cost of the concentrators, shorten the upgrading time and ensure the upgrading safety.