Abstract: The optimized configuration of thick-wall drag brace was designed according to the permissibility of composites and the characteristics of resin transfer molding (RTM) process. The permeability of the preforms was measured and the RTM process was investigated by the numerical simulation. The RTM mold was manufactured based on the results of the flow simulation. A specimen of thick-wall drag brace was successfully manufactured via RTM process and the specimen was evaluated by mechanical test. The mechanical results show that the drag brace designed based on the numerical simulation well meet the manufacturing and loading requirements.