Within the framework of the European DEMO blanket study programme, this paper describes the design work performed on the “box-shaped” concept for water-cooled Pb-17Li blankets in the past two years. The first part of the paper describes the general design, and the thermo-mechanical and neutronical analyses of the main segment structure leading to the optimization of the thickness of the various component. The second part describes specific analysis of particular segment regions, like water-and Pb-17Li-headers, box bottom and support, which have required detailed design development. All results indicate that the “box-shaped” concept is a very promising candidate for DEMO reactor blankets.