Embodiments of the present invention disclose a method for updating a group temporal key, a related apparatus and system. A method includes: An access point AP sets an updating period of a group temporal key GTK; the access point updates the GTK whenever the updating period of the GTK arrives; the access point receives a GTK request that is sent by a mobile station STA in an association list within a preset delay time period after arrival of the updating period of the GTK, where the association list records all mobile stations communicating with the access point, and the preset delay time period is shorter than the updating period of the GTK; and when the preset delay time period after the arrival of the updating period of the GTK arrives, the access point sends the updated GTK to the mobile station in the association list according to the GTK request.