Water stored in a dam has far larger potential energy than the flow-water in river before banking. So, it is important to dissipate energy in water flowing over dam, chute and other hydraulic structures and thus prevent scouring downstream from structures. From a practical viewpoint, hydraulic jump is a useful means of dissipating the energy. The hydraulic jump used for energy dissipation is usually confined to the stilling basin. Furthermore, in order to control the jump, the accessories are usually installed in the basin to shorten the range in which the jump will take place. In this investigation, subdam was used as accessory to control the jump. The objective of this study was to investigate the methods for determining the height of subdam, its setting place, and its downstream depth.