Abstract: The toroidal field (TF) and poloidal field (PF) magnets are critical components of the International Thermonuclear Experimental Reactor (ITER). During the performance verification of the TF and PF magnets on the magnet cryogenic test bench (MCTB), structural supports are required to maintain the magnets' positioning. To minimize the impact of excessive thermal loads generated by the supports on the experimental results, it is particularly crucial to optimize the design of their thermal insulation structures. Based on the structural characteristics of the TF and PF magnets, two different types of support structures were developed in this study, incorporating independent cooling plates combined with G10 insulation plates as the thermal insulation system. To evaluate the performance of the insulation structure, numerical simulations of the liquid helium outlet temperature were conducted using Fluent software. The obtained average temperatures at the channel walls were subsequently applied as boundary conditions in a steady-state thermal analysis using Workbench to calculate the thermal loads imposed on the magnets. Simulation results demonstrate that the designed insulation structures meet the thermal insulation performance requirements, providing a reference for the design and performance validation of support systems in large-scale cryogenic facilities.