The present disclosure provides a method and a device in a User Equipment (UE) and a base station for wireless communications. The UE receives a first signaling, and then transmits a first radio signal in a first subband. The first signaling comprises scheduling information of the first radio signal; the first signaling comprises a first field, the first field in the first signaling being used for determining a first reference-signal-resource group or the first subband, the first reference-signal-resource group comprising K1 first-type reference signal resource(s); whether the scheduling information of the first radio signal is non-codebook-based or codebook-based is related to the first field in the first signaling; the first subband is one of M subbands. The above method allows UE to flexibly switch between non-codebook-based and codebook-based uplink transmissions, thus avoiding the problem that a single uplink transmission mode cannot work on Unlicensed Spectrum.