The present disclosure provides a method and a device in a communication node for wireless communications. A communication node receives first information, and the first information is used to determine a first payload size; monitors a first signaling in a target search space, a payload size of a payload of the first signaling is equal to a target payload size; the target search space is used to determine X payload size(s), the target payload size is equal to one of X payload size(s); when there exists one of the X payload size(s) being not less than the first payload size, the target payload size is equal to a payload size among the X payload size(s) which is closest to and not less than the first payload size. The application improves the performance of control signalings.