The disclosure provides a method and a device in a User Equipment (UE) and a base station for wireless communication. The UE receives first information, and transmits a first radio signal using a first antenna port group; the first information is used for indicating a first offset set, and the first offset set includes K1 first-type offset(s); time domain resources occupied by the first radio signal start from a first time, a time interval between the first time and a second time is equal to a target offset; the UE selects the target offset from the K1 first-type offset(s) autonomously. The disclosure establishes a relationship between the first offset set and the first antenna port group, thus improving opportunities of beamforming based grant-free data transmission on unlicensed spectrum and reducing probability of collision, thereby improving spectrum efficiency and overall performances of the system.