This application provides a transmission method and device. The method includes: receiving, by a first device, a first RRC message sent by a second device, where the first RRC message includes first data and identification information, and then sending, by the first device, the first data and the identification information to a donor eNB of the first device by using a second RRC message. Because the first device and the second device send data by using an RRC message, network functions of the first device and the second device are simplified, and data transmission efficiency is increased after a plurality of relay nodes access an NB-IoT network.