Provided are a method for updating system information, a terminal, and a network side device. The method includes that: a terminal acquires at least one piece of indication information sent by a network side device, the at least one piece of indication information being configured to indicate that at least one system information group is updated, the at least one system information group being in one-to-one correspondence with the at least one piece of indication information, each system information group of the at least one system information group including at least one piece of system information; the terminal determines at least one piece of updated target system information in the at least one system information group; and the terminal acquires the at least one piece of updated target system information. The embodiments of the present disclosure indicate updates of different system information groups via different indication information.