<p>Multi-component structures are commonly assembled by smaller components, which can be flexibly designed and manufactured in engineering. Generally, it is difficult to consider the multi-component design obtained by adjustable connections in topology optimization. Therefore, this paper proposes a topology optimization method for multi-component assemblies and connections in the solid isotropic material with penalization (SIMP) framework. The topological distributions of components and connections are optimized simultaneously. Connections are simulated using the rigid body element 2 (RBE2) in the finite element model. Because the RBE2 lacks the concept of material density, a pseudo-density is ingeniously defined as the average density of the connected elements. The topology optimization formulation minimizes the structural compliance, subject to separate volume fraction constraints for components and connections. The design variables are updated using the optimality criteria method. Numerical examples demonstrate that the proposed method not only yields optimal topological distributions of connections, but also effectively separates large components into small and manufacturable components. Therefore, the proposed method enables flexible design and manufacture to avoid the use of large dies.</p>