A method for upgrading a device through multicast is disclosed. The method includes: monitoring a common channel of a multicast server, where information about all subfiles of a current packaged mirror file is multicast in the common channel; obtaining information about a subfile required for upgrading the device from packets in the common channel, where the information includes an address of a subchannel that bears the subfile on the multicast server; and switching to the subchannel according to the address of the subchannel that bears the subfile required for upgrade, receiving the subfile multicast in the subchannel, and validating the subfile. Further, an apparatus and system for upgrading a device through multicast are disclosed. The technical solution under the present invention can upgrade both a single-system or single-module device and a multi-system or multi-module device through multicast, the time required for upgrading the devices is reduced, and the upgrade status of the devices can be tracked in real time.