Purpose <p>This study investigates the coexistence and transition characteristics of attractors in a class of single-degree-of-freedom vibro-impact systems with different constraints. Special attention is paid to the mechanisms responsible for the formation, evolution, and disappearance of coexisting attractors under non-smooth bifurcation behaviors.</p> Methods <p>A theoretical and numerical framework combining Floquet theory, the shooting method, parameter continuation algorithms, cell mapping, and multi-parameter joint simulations is employed. The Jacobian matrix of the Poincaré map is derived through the construction of local mappings. The distribution and stability of coexisting attractors are then determined in the parameter plane, and the transition processes between different attractors are analyzed.</p> Results <p>The results reveal that saddle-node bifurcations occur in the vicinity of grazing and period-doubling bifurcation points, leading to saddle-node grazing bifurcations and saddle-node period-doubling bifurcations. These bifurcations generate both stable and unstable attractors, resulting in multistability and coexistence phenomena. It is further shown that the emergence and disappearance of coexisting attractors are caused by collisions between stable and unstable attractors, as well as interactions between chaotic attractors and unstable periodic attractors. In particular, boundary crises are found to induce the sudden destruction of chaotic attractors.</p> Conclusion <p>The coexistence and transition of attractors in vibro-impact systems with different constraints are governed by complex interactions among saddle-node bifurcations, grazing bifurcations, period-doubling bifurcations, and boundary crises. The findings provide deeper insight into the nonlinear dynamics of non-smooth mechanical systems and offer useful guidance for parameter design, vibration reduction optimization, and dynamic control of engineering systems with clearances.</p>