Abstract <p>Aiming at the problems in existing studies on thin-walled multi-branch tubes, such as unclear intrinsic correlations between wall thickness, number and length of internal supports and dynamic/static mechanical responses, as well as the lack of coupling effects, this study systematically investigated the mechanical behaviors and energy absorption characteristics of thin-walled multi-branch tubes with internal supports. 6061-T6 aluminum alloy was selected as the specimen material, and the study adopted a combined method of quasi-static compression tests, drop hammer impact tests, and finite element analysis (FEA). The effects of wall thickness, number and length of internal support ribs, and impact angle on stress distribution, deformation modes, energy absorption, and specific energy absorption (SEA) were analyzed. The results show that increasing the number of internal branches significantly improves the energy absorption efficiency, with a maximum increase of 300%, and reduces the sensitivity to load direction. Increasing the wall thickness can enhance the peak load, but it is necessary to simultaneously increase the number of internal supports to improve the energy absorption effect. Shortening the length of the support ribs will weaken the energy absorption effect. Finally, under quasi-static and impact conditions, L-8-B exhibits stable load performance and high specific energy absorption, making it the optimal protective structure. This study provides a reference for the optimal design of energy absorption for multi-branch tubes.</p>