A method and a device in a UE and a base station for wireless communication are disclosed. The UE monitors a first sequence in a first time window. If the first sequence is detected in the first time window, performs a blind detection of a first signaling on K1 alternative RE set(s); the first signaling occupies one of K1 alternative RE set(s) in time-frequency domain, each RE included in K1 alternative RE set(s) belongs to an alternative time-frequency resource pool in a second time window in time domain. The first sequence is used for determining a start time of the alternative time-frequency resource pool in the second time window. The disclosure determines the start time of the alternative time-frequency resource pool by using the first sequence, increasing transmitting opportunities of control signalings without increasing number of times of blind detections, improving spectrum efficiency and overall system performance on unlicensed spectrum.