The invention discloses a method for upgrading firmware of an electric energy meter by adopting a multicast communication mode, which is characterized by comprising the following steps that: superiorequipment sends an upgrading request to the electric energy meter, acquires the electric energy meter to be upgraded according to the upgrading request, and groups the electric energy meters to be upgraded; the superior equipment transmits an upgrading file to the to-be-upgraded electric energy meter in a multicast communication mode; and after the to-be-upgraded electric energy meter successfullyreceives the upgrading file, firmware upgrading is carried out according to an upgrading instruction sent by superior equipment, so that the problems of long time consumption and incapability of timely completing firmware upgrading of a large batch of electric energy meters at present are solved.