A magnet cold test bench (MCTB) is being developed to accommodate the PF1 and TF superconducting coils of the International Thermonuclear Experimental Reactor, ensuring that performance evaluations are conducted under the required vacuum and cryogenic conditions. As the primary load-bearing components, the magnet supports in the MCTB must withstand gravitational forces from the coils, thermal and significant electromagnetic loads during testing. Their structural integrity is thus critical to the safety and reliability of the test system. This study presents a systematic design and evaluation of the MCTB magnet supports. The results indicate that the supercritical helium-cooled magnet supports exhibit excellent thermal insulation performance, with total heat load through the support–coil interfaces for each coil significantly below the design threshold (⩽400 W). In addition, a multi-physics coupled simulation is conducted to evaluate the structural integrity of the key load-bearing components and bolts, confirming compliance with applicable design standards. A buckling analysis further verifies the structural stability of the major load-bearing elements under extreme loading conditions. Finally, the capacity of the supports to absorb impact from the potential vertical drop of the TF coil is evaluated based on energy conversion principles. The results show that the support structure can safely withstand a 1.3 mm drop of the TF coil. If the integrity of the MCTB cryostat shell is not considered, the structure can theoretically sustain a TF coil drop of over 14 mm. These drop analysis results also provide essential quantitative support for the safe installation of the TF coil prior to testing. The design and validation approaches proposed in this study offer valuable technical insights for the development of large superconducting coil support structures in future fusion devices.