Abstract: Topology optimization design of minimum weight cantilever trusses subjected to stress constraints is studied. First, the fully stressed truss-like continuum structures are established by analytical method and finite element method based on Michell’s theory. Second, the continuum structures are discretized to trusses as near optimum structures by selecting parts of members. The topology optimization problems are formulated and solved. It is proved that in the topology optimum trusses, the midst nodes of web members locate at one fourth of the panel length. The trusses subjected to two point forces at their tips and subjected to uniform distribution forces at their sides are optimized by analytical and numerical methods. The optimum numbers and lengths of panels are obtained. These optimum trusses are lighter over 20% than the trusses with web members of , which are frequently used in engineering.