Through investigating the prototype materials and th eoretical analyses of some completed gravity dams in which the composite energy dissipation systems of stilling basins with flaring gate piers of the surface ou tlets have been adopted,the study results show that the flaring gate piers can p lay the roles of increasing the threedimension character of water jet ,decreas ing the secondary conjugate depth of water jump,and thus the basin floor can be made higher and its length shorter.It is that this kind of energy di ssipation system may be used for the Zhaoshi Project. 