Recently, the construction of the large astronomical telescope has been planned for better astronomical observation. In this project, it is necessary to design the structure of the telescope economically as well as easy to construct. Additionally homogeneous deformation of the supporting structure of the telescope is desirable to realize the stable supporting system of the main system of the telescope. However it is not so easy to design such structure, because the various tilt angle caused by the rotation of telescope for astronomical observation result in the large amount of the change in the external load. In this paper, the scheme of multi-objective optimal design for truss structures supporting large telescope are proposed and demonstrated in an actually constructed 3.8 m telescope. Using SPEA2 as multi-objective optimal method, where standard deviation of nodal displacements is adopted to evaluate homologous deformation, simultaneously satisfies the requirement of both weight minimization and homologous deformation.
