Embodiments of the present invention disclose a link re-establishment method and a device, and relate to the communications field: When detecting that a first downlink beam pair set is invalid, UE sends a first uplink signal to a base station at a moment n by using a first uplink beam pair set through a first uplink channel, where the first uplink signal is used to notify the base station that the first downlink beam pair set is invalid; and the UE detects, at a moment n+k, a first downlink signal sent by the base station by using a second downlink beam pair set through a first downlink channel.