A method and a device in a communication node used for wireless communications is disclosed in the present disclosure. The communication node first receives first information and second information; and transmits a first radio signal in a first time window; and then transmits a second radio signal; the first information is used to determine a target time window, the second radio signal occupies a second time window in time domain, and the second information is used to determine at least one of whether the second time window belongs to the target time window or a relative position relationship between the second time window and the target time window; an end of the first time window is earlier than a start of the target time window. The present disclosure helps improve the utilization ratio of resources in Grant-Free transmission.