This first author of thes paper is one of four winners fo the 2005 Hangai Prize, awarded for outstanding papers that are submitted for proemtaton and publication at the 2005 Hangai Prize, awarded for outstanding papers that are submitted for proaentation and publication at the annuai IASS Symposium by younger members of the association (under 30 yesrs old). It is republished here with the permission of the editors of the proceedings of the proceedings of the IASS 2005 Symposium on Shell and Spatial Structures-Theory, Technique, Valuation, Maintenance, held in September 2005 in Bucharest, Romania. This paper presents the structural design of Samoa Aquatic Center. Some curves are built to form the doublecurved surface of the roof. Furthermore. roof structure is composed of runthrough circular or rectangular hollow section steel tubes truss. The structure is analyzed in three-dimensional finite-element model. Through this way, some important data, such as displacement and vibrating period of structure, are obtained The mutual effect of steel roof and the supporting concrete frames is considered in this paper. The data which obtained respectively from 3D3S7.0 and Ansys 7.1 are compared. It can draw a conclusion that the structure is safe enough to fulfill its function of practical employment. In addition, several important joints are designed in detail. Practical application proves these joints are advantageous.