1. A method, comprising:receiving, by second user equipment (UE), a first message from first UE, wherein the first message comprises relay request information;
determining, by the second UE according to the first message, whether a preset first condition is satisfied, wherein the preset first condition comprises: network status information of the first UE indicating that the first UE is unable to directly perform data transmission with a base station, or signal quality between the second UE and the base station being lower than a first threshold and higher than a second threshold;
when determining that the preset first condition is satisfied, sending, by the second UE, a second message to the base station according to the first message, wherein the second message comprises information indicating that the second UE requests to act as relay UE for data transmission between the first UE and the base station; and
receiving, by the second UE, a third message from the base station, wherein the third message instructs the second UE to act as the relay UE.