The present disclosure provides a method and a device in a base station used for wireless communication. The base station transmits M1 first-type reference signals; receives M2 second-type radio signals in first time-domain resources, with any of the M2 second-type radio signals being associated with one of the M1 first-type reference signals; and transmits a first radio signal in the first time-domain resources. If an antenna port transmitting the first radio signal is associated with at least one of the M2 second-type radio signals, first-type channel monitoring is adopted targeting transmission of the first radio signal; otherwise, second-type channel monitoring is adopted targeting transmission of the first radio signal. The above method allows the base station to share a COT acquired by a UE in unlicensed spectrums so as to increase channel access efficiency, and at the same time avoids interference with other potential ongoing communications.