Lightweight technology refers to the technology of reducing the weight of structures by optimizing materials， structures， and manufacturing processes while meeting structural performance requirements. It has become one of the key technologies for the development of a new generation aerospace equipment. This paper firstly analyzes the development process of lightweight technology. Secondly， from the perspectives of design principles， composition methods， and optimization methods， three lightweight design methods are reviewed in detail： bionic structure design， cellular structure design， and efficient topology optimization design. Then， the applications of additive manufacturing， collaborative manufacturing， and composite material manufacturing in the lightweight manufacturing of aerospace structures are introduced from the perspectives of lightweight manufacturing processes and modes. Finally， the challenges and development prospects of lightweight technology are discussed.