An excavation is used to construct a basement for construction and building. Under different soil conditions, an earth retaining wall must be installed along the excavation to prevent the collapse of the soil due to the excavation and soil condition. The paper presents a strut-free earth retaining wall system for excavation in soft clay, referred to as the rigid and fixed diaphragm (RFD) wall retaining system. diaphragm walls, rib-walls, cross walls, and buttress walls are main components of rigid and fixed diaphragm. Furthermore, the performance and mechanisms of the RFD system were investigated carefully through finite element analyses using PLAXIS 3D. The safety factor of the RFD system using an elastoplastic and elastic plate element is conducted and compared to each other. Also, the effect of excavation geometry has a significant effect on dimension of RFD system components.