Abstarct: Investigating of structural analysis and optimal design as well as their integration, is the aim of this research. For this purpose, in the first parts of the thesis, the isogeometric approach is developed for the linear elastic analysis of shell structures. In the following parts, structural shape and topology optimization is investigated. In the analysis parts, introduction of the NURBS function as well as the isogeometric analysis is followed by the formulation of shell structures. The idea of curvilinear coordinate system is utilized for shell isogeometric analysis. The approach is baxsed on the Mindlin-Reissner theorem. Three displacement and two rotational degree of freedoms is assigned to each control point. Different examples containing free form shell and shell obstacles, are presented to demonstrate the performance of the method. The idea of SIMP is used for topology optimization. The NURBS functions are used to approximate a density function over the design domain. The control values of this function are used as design variables in optimization problem. Some examples of plane and shell structures, demonstrates the well perforemance of the method. The coordinates of control points are considered as design variables in shape optimization problem. By refining the design control mesh, a finer mesh is generated for the analysis procedure. It means that two different models are used for design and analysis. In the final part, the simultaneous shape and topology optimization of the shell structures is presented. This approach is first considered for a discrete finite element model. Finally this integrated method is used for isogeometric baxsed approach. It means that all the analysis, shape and topology parameters are formulated by using NURBS functions. It is demonstrated that the integrated approach leads to better results than the seperated shape and topology optimization.