A data transmission method, the method being characterized by: obtaining, by an access network device, waiting duration corresponding to transmitting uplink data of a first subframe quantity by a terminal, wherein the first subframe quantity is a number of first subframes, wherein the first subframe quantity is a subframe quantity with greatest scheduling efficiency within a preset subframe quantity value range when the access network device schedules the terminal to transmit the uplink data, the preset subframe quantity value range is a subframe quantity value range of subframes that can be transmitted by the terminal once, and the waiting duration is duration that exists after the terminal transmits the uplink data and that is from a time at which the terminal switches to a listening state to a time at which the terminal detects an uplink authorization instruction; if the obtained waiting duration corresponding to transmitting the uplink data of the first subframe quantity by the terminal is greater than a threshold, determining, by the access network device within the preset subframe quantity value range, a second subframe quantity that enables the waiting duration corresponding to transmitting the uplink data by the terminal to be less than or equal to the threshold; and sending, by the access network device, a first uplink authorization instruction to the terminal, wherein the first uplink authorization instruction is used to instruct the terminal to send uplink data of the second subframe quantity, wherein the second subframe quantity is a number of second subframes; wherein the waiting duration is determined by using the following formula: t 5 = t x − t 1 + t 2 + t 3 + t 4, where t 5 is the waiting duration, t 1 is transmitting duration of a further uplink authorization instruction received before the terminal transmits the uplink data, and the terminal determines, by using the further uplink authorization instruction, the subframe quantity required for the transmission, t 2 is duration in which the terminal switches from the listening state to a data transmission state, t 3 is further duration in which the terminal transmits the uplink data, where the further duration is determined based on an uplink subframe quantity indicated in the further uplink authorization instruction received from t 1, t 4 is duration in which the terminal switches from the data transmission state to the listening state, t x is duration from a starting time of t 1 to a starting time of the first uplink authorization instruction received after the terminal switches to the listening state; and wherein the scheduling efficiency is determined based on the following formula: S = d / t 1 + t 2 + t 3 + t 4; where S is the scheduling efficiency, and d is a bit quantity of bits that are included in the uplink data transmitted by the terminal in t 3. obtaining, by an access network device, waiting duration corresponding to transmitting uplink data of a first subframe quantity by a terminal, wherein the first subframe quantity is a number of first subframes, wherein the first subframe quantity is a subframe quantity with greatest scheduling efficiency within a preset subframe quantity value range when the access network device schedules the terminal to transmit the uplink data, the preset subframe quantity value range is a subframe quantity value range of subframes that can be transmitted by the terminal once, and the waiting duration is duration that exists after the terminal transmits the uplink data and that is from a time at which the terminal switches to a listening state to a time at which the terminal detects an uplink authorization instruction; if the obtained waiting duration corresponding to transmitting the uplink data of the first subframe quantity by the terminal is greater than a threshold, determining, by the access network device within the preset subframe quantity value range, a second subframe quantity that enables the waiting duration corresponding to transmitting the uplink data by the terminal to be less than or equal to the threshold; and sending, by the access network device, a first uplink authorization instruction to the terminal, wherein the first uplink authorization instruction is used to instruct the terminal to send uplink data of the second subframe quantity, wherein the second subframe quantity is a number of second subframes; wherein the waiting duration is determined by using the following formula: t 5 = t x − t 1 + t 2 + t 3 + t 4, where t 5 is the waiting duration, t 1 is transmitting duration of a further uplink authorization instruction received before the terminal transmits the uplink data, and the terminal determines, by using the further uplink authorization instruction, the subframe quantity required for the transmission, t 2 is duration in which the terminal switches from the listening state to a data transmission state, t 3 is further duration in which the terminal transmits the uplink data, where the further duration is determined based on an uplink subframe quantity indicated in the further uplink authorization instruction received from t 1, t 4 is duration in which the terminal switches from the data transmission state to the listening state, t x is duration from a starting time of t 1 to a starting time of the first uplink authorization instruction received after the terminal switches to the listening state; and wherein the scheduling efficiency is determined based on the following formula: S = d / t 1 + t 2 + t 3 + t 4; where S is the scheduling efficiency, and d is a bit quantity of bits that are included in the uplink data transmitted by the terminal in t 3.