A method, a device, and a system for sending and receiving messages are provided. The method for sending messages includes: receiving, by a Mobility Management Entity (MME), an Earthquake and Tsunami Warning System (ETWS) message; setting an information change identifier if the received ETWS message is different from the ETWS message stored by the MME; and sending the received ETWS message and the information change identifier. In the embodiments of the present disclosure, the MME decides whether to send the ETWS message to the eNB. Therefore, the eNB needs only to transmit the received message to the UE transparently, and does not need to judge the content of the ETWS message, thus simplifying the process of the eNB sending the ETWS message and reducing the load of the access network device.