A method of message retransmission and a user equipment (UE) using the same are provided, which are adapted for performing a discovery procedure of the proximity service (ProSe). The UE includes a transceiver and a processor. The transceiver is used to transmit and receive a wireless signal. The processor is coupled to the transceiver and configured to perform the following steps. A first message used for an authorization request of the ProSe is transmitted through the transceiver, and a first timer is started. If a second message responding to the first message is not received through the transceiver when the first timer is expired, a second timer is started. And, the first message is not transmitted through the transceiver before the second timer is expired.