Focus of attention instruction has a great influence on performance and learning. The purpose of this study was to examine the predicted constrained action hypothesis in badminton backhand serv. 30 women student participants from physical education classes of University of Kharazmi are selected as sample. Participants are tested in probe task at different stage of serve after identifying base of reaction time, and level of attention demanding of different parts was measured. Then participants divided into two groups (internal and external focus of attention) and they are tested with their specific instruction again. The results revealed that first stage of serve has the most attention need (p<0/001), but there is not any difference between two groups and different serve stage in the effect of focus of attention type. Accordance with these results the constrained action hypothesis at discrete skills is not confirmed.