According to a method and apparatus for controlling data transmission in a wireless communications network, a service quality request message is sent to a PCRF when a data request message of a terminal is received; and the PCRF queries a current network status, so as to determine a processing instruction for a data request message of the terminal according to the current network status and the data request message, and process the data request message of the terminal according to the processing instruction. Therefore, processing on the data request message of the terminal not only depends on a parameter carried in the data request message of the terminal, but also uses the current network status as a constraint condition, so that a processing manner for the data request message can be adaptive to a real-time change of the wireless communications network.