A service data transmission method, wherein the method comprises: obtaining, by a first communications node and sent from a base station, transmission carrier frequency configuration information of a first service type, wherein the transmission carrier frequency configuration information of the first service type comprises at least one first transmission carrier frequency identifier, and a transmission carrier frequency corresponding to the at least one first transmission carrier frequency identifier is used to transmit service data of the first service type; obtaining, by the first communications node, first service data and a first identifier, wherein the first identifier is used to indicate that the first service data belongs to the first service type, wherein the obtaining, by the first communications node, first service data and a first identifier comprises: obtaining, by the first communications node, the first service data and the first identifier that are sent at a protocol layer above an access stratum; determining, by the first communications node based on the first identifier and the at least one first transmission carrier frequency identifier, a first transmission carrier frequency used to transmit the first service data; and transmitting, by the first communications node, the first service data on the first transmission carrier frequency; characterised in that the transmission carrier frequency configuration information of the first service type further comprises a second identifier corresponding to the at least one first transmission carrier frequency identifier; and the determining, by the first communications node based on the first identifier and the at least one first transmission carrier frequency identifier, a first transmission carrier frequency used to transmit the first service data comprises: when the first identifier is equal to the second identifier, determining, by the first communications node based on the at least one first transmission carrier frequency identifier corresponding to the second identifier, the first transmission carrier frequency used to transmit the first service data. obtaining, by a first communications node and sent from a base station, transmission carrier frequency configuration information of a first service type, wherein the transmission carrier frequency configuration information of the first service type comprises at least one first transmission carrier frequency identifier, and a transmission carrier frequency corresponding to the at least one first transmission carrier frequency identifier is used to transmit service data of the first service type; obtaining, by the first communications node, first service data and a first identifier, wherein the first identifier is used to indicate that the first service data belongs to the first service type, wherein the obtaining, by the first communications node, first service data and a first identifier comprises: obtaining, by the first communications node, the first service data and the first identifier that are sent at a protocol layer above an access stratum; determining, by the first communications node based on the first identifier and the at least one first transmission carrier frequency identifier, a first transmission carrier frequency used to transmit the first service data; and transmitting, by the first communications node, the first service data on the first transmission carrier frequency; characterised in that the transmission carrier frequency configuration information of the first service type further comprises a second identifier corresponding to the at least one first transmission carrier frequency identifier; and the determining, by the first communications node based on the first identifier and the at least one first transmission carrier frequency identifier, a first transmission carrier frequency used to transmit the first service data comprises: when the first identifier is equal to the second identifier, determining, by the first communications node based on the at least one first transmission carrier frequency identifier corresponding to the second identifier, the first transmission carrier frequency used to transmit the first service data. obtaining, by the first communications node, the first service data and the first identifier that are sent at a protocol layer above an access stratum; determining, by the first communications node based on the first identifier and the at least one first transmission carrier frequency identifier, a first transmission carrier frequency used to transmit the first service data; and transmitting, by the first communications node, the first service data on the first transmission carrier frequency; characterised in that the transmission carrier frequency configuration information of the first service type further comprises a second identifier corresponding to the at least one first transmission carrier frequency identifier; and the determining, by the first communications node based on the first identifier and the at least one first transmission carrier frequency identifier, a first transmission carrier frequency used to transmit the first service data comprises: when the first identifier is equal to the second identifier, determining, by the first communications node based on the at least one first transmission carrier frequency identifier corresponding to the second identifier, the first transmission carrier frequency used to transmit the first service data.