A method for monitoring a link, applied to a first terminal device, wherein the method comprises: establishing a Bluetooth asynchronous connectionless link ACL with a second terminal device, wherein the first terminal device is a slave and the second terminal device is a master, and the first terminal device has established a wireless fidelity Wi-Fi link; wherein the Bluetooth ACL and the Wi-Fi link share the same antenna for data transmission; determining a preset parameter of the first terminal device and/or the second terminal device; determining, based on the preset parameter, whether to perform role switch; sending a first request message to the second terminal device when it is determined to perform role switch, wherein the first request message is used to request role switch between the first terminal device and the second terminal device, and a Bluetooth time-sharing ratio of the master per unit time is lower than that of the slave per unit time; receiving, by the first terminal device, a first response message from the second terminal device, wherein the first response message is used to confirm or reject the role switch with the first terminal device; and when it is determined to perform the role switch, monitoring the Bluetooth ACL based on a first Bluetooth time-sharing ratio, wherein the first Bluetooth time-sharing ratio is lower than a second Bluetooth time-sharing ratio used by the first terminal device to monitor the Bluetooth ACL before the role switch; wherein the preset parameter comprises at least one of the following: Wi-Fi data transmission flow and/or Bluetooth data transmission flow of the first terminal device; or a power consumption increment of the first terminal device acting as a master; or an electricity quantity of the first terminal device; or an electricity quantity of the second terminal device; or a capability of the second terminal device acting as a slave; or a performance reduction of the second terminal device acting as a slave. establishing a Bluetooth asynchronous connectionless link ACL with a second terminal device, wherein the first terminal device is a slave and the second terminal device is a master, and the first terminal device has established a wireless fidelity Wi-Fi link; wherein the Bluetooth ACL and the Wi-Fi link share the same antenna for data transmission; determining a preset parameter of the first terminal device and/or the second terminal device; determining, based on the preset parameter, whether to perform role switch; sending a first request message to the second terminal device when it is determined to perform role switch, wherein the first request message is used to request role switch between the first terminal device and the second terminal device, and a Bluetooth time-sharing ratio of the master per unit time is lower than that of the slave per unit time; receiving, by the first terminal device, a first response message from the second terminal device, wherein the first response message is used to confirm or reject the role switch with the first terminal device; and when it is determined to perform the role switch, monitoring the Bluetooth ACL based on a first Bluetooth time-sharing ratio, wherein the first Bluetooth time-sharing ratio is lower than a second Bluetooth time-sharing ratio used by the first terminal device to monitor the Bluetooth ACL before the role switch; wherein the preset parameter comprises at least one of the following: Wi-Fi data transmission flow and/or Bluetooth data transmission flow of the first terminal device; or a power consumption increment of the first terminal device acting as a master; or an electricity quantity of the first terminal device; or an electricity quantity of the second terminal device; or a capability of the second terminal device acting as a slave; or a performance reduction of the second terminal device acting as a slave. Wi-Fi data transmission flow and/or Bluetooth data transmission flow of the first terminal device; or a power consumption increment of the first terminal device acting as a master; or an electricity quantity of the first terminal device; or an electricity quantity of the second terminal device; or a capability of the second terminal device acting as a slave; or a performance reduction of the second terminal device acting as a slave.