Definition method of element field and device

The embodiment of the invention discloses a definition method of an element field and a device, relating to the field of communication technology. The method comprises a step of adding a beacon number or the beacon number and a target site for an element field, wherein the beacon number is used for indicating a beacon frame period number of a site from the reception of the beacon frame to which the element field belongs to the occurrence of a triggered event, and the element field is an element identification number, a length and the content of the triggered event from a field head to a field tail, and a step of broadcasting the beacon frame with the element field. The method and the device are suitable for the interaction between an access point in a wireless LAN system and a site.