Methods and apparatuses for handling sensing for a sidelink source in a wireless communication system are disclosed herein. In one method, a User Equipment (UE) receives a control signaling which schedules a resource of a first transmission, in which the control signaling informs and/or indicates that the scheduled resource is not kept for a next transmission. The UE performs energy sensing for candidate resources, in which one or more resources associated with the scheduled resource of the first transmission is not utilized for energy sensing.