A method and an apparatus for controlling data transmission can reduce occurrence of collisions between stations. The method includes: determining at least one first station; and sending first indication information to the first station, where the first indication information is used for indicating at least one first backoff duration, so that the first station performs a data transmission operation by using the first backoff duration, and the first backoff duration used by the first station to perform a data transmission operation is less than a second backoff duration used by a second station to perform a data transmission operation, or the first backoff duration used by the first station to perform a data transmission operation is greater than the second backoff duration used by the second station to perform a data transmission operation. Shortening backoff durations of some stations can ensure that these stations send data first, and extending backoff durations of some stations can ensure that the other stations send data first. Therefore, occurrence of collisions between the stations can be reduced.