Service data transmitting method and system

The invention discloses a service data transmitting method and a service data transmitting system. The service data transmitting method comprises the following steps that: a sending station sends a wireless frame and informs group transmission time interval information; group stations receive the wireless frame and acquire the group transmission time interval information belonging to groups; and the group stations competitively send information within group transmission time intervals belonging to the groups, and a station, which gets a sending change, in the group stations sends the wireless frame in the sending chance acquired by competition. By the method, the sending station distributes the group transmission time intervals to different groups of stations; under the condition of a large number of user stations, different groups of user stations compete for channels in different time intervals, so that simultaneous or similarly simultaneous competition between a large number of users is avoided, the collision probability is reduced, and the utilization efficiency of wireless resources is improved.