The disclosure provides a method and a device in a User Equipment (UE) and a base station for wireless communication. The UE first receives a first signaling, the first signaling being used for determining a number of bits included in a first bit block; then the UE performs first listening to determine that a first frequency-domain resource set is available for wireless transmission; and finally the UE transmits a first radio signal in a first time-domain resource set of the first frequency-domain resource set; a second bit block is used for generating the first radio signal, and the second bit block is obtained after the first bit block is processed through channel coding; and the first time-domain resource set is related to a number of bits not transmitted in a current second bit block and the first frequency-domain resource set. The disclosure improves opportunities of transmission on unlicensed spectrum.