The optimization method of mechanical structures is comprehensively introduced in this book. The book includes the dynamic simulation modeling method and structural dynamic response optimization of spectral element method for different dynamic problems, structural dynamic response optimization considering equivalent static load method of all nodes, and structural static optimization combining elements of optimum methods with structural geometric and engineering requirements. This book is rich in its content; it covers a new frontier and operability. It can be used as a reference for engineers engaged in the mechanical system or structural analysis and optimization design, and as a reference textbook for graduate or senior undergraduate mechanical structure's optimization courses.