Provided are information interaction methods, devices and system for a Wireless Body Area Network (WBAN). The method includes that: a Hub sends beacon frames to nodes according to a preset superframe structure and receives, according to a preset superframe structure, information sent by the nodes. The preset superframe structure includes three phases. The first phase includes a first beacon period, a first timeslot period and a second timeslot period, the first timeslot period being used by nodes to send an emergency service and the second timeslot period being used by nodes to send an ordinary service. The second phase includes a second beacon period and a third timeslot period, the third timeslot period being used by nodes to complementarily send a service. The third phase includes a fourth timeslot period, the fourth timeslot period being used by nodes to send a sleep application and/or an access application.