A data transmission method of a wireless network, comprising the steps of: receiving, by a station, an indication frame sent by an access point, wherein the indication frame is used for allocating a designated random contention channel (Step 101), wherein the station and the access point are arranged in the wireless network and wherein the indication frame further includes information of a designated station group, wherein each station in the designated station group can detect a signal of another station in the group; sensing, by the station, according to the indication frame, a channel state of the designated random contention channel (Step 102); and sending, by the station, data on the designated random contention channel after it is detected that the designated random contention channel is in an idle state (Step 103); wherein the step of sending, by the station, data on the designated random contention channel after it is detected that the designated random contention channel is in an idle state, comprises the step of: determining, by the station, whether the station belongs to the designated station group; and if it is determined, by the station, that the station belongs to the designated station group, executing, by the station, backoff on the designated random contention channel after it is detected that the designated random contention channel is in an idle state and sending, by the station, data on the designated random contention channel after a backoff time of the station ends. receiving, by a station, an indication frame sent by an access point, wherein the indication frame is used for allocating a designated random contention channel (Step 101), wherein the station and the access point are arranged in the wireless network and wherein the indication frame further includes information of a designated station group, wherein each station in the designated station group can detect a signal of another station in the group; sensing, by the station, according to the indication frame, a channel state of the designated random contention channel (Step 102); and sending, by the station, data on the designated random contention channel after it is detected that the designated random contention channel is in an idle state (Step 103); wherein the step of sending, by the station, data on the designated random contention channel after it is detected that the designated random contention channel is in an idle state, comprises the step of: determining, by the station, whether the station belongs to the designated station group; and if it is determined, by the station, that the station belongs to the designated station group, executing, by the station, backoff on the designated random contention channel after it is detected that the designated random contention channel is in an idle state and sending, by the station, data on the designated random contention channel after a backoff time of the station ends. determining, by the station, whether the station belongs to the designated station group; and if it is determined, by the station, that the station belongs to the designated station group, executing, by the station, backoff on the designated random contention channel after it is detected that the designated random contention channel is in an idle state and sending, by the station, data on the designated random contention channel after a backoff time of the station ends.