Resin transfer molding (RTM) process has been gaining extensive attention because of its ability to produce complex structural composite parts. Researchers have made significant progress toward obtaining quality products. The preform permeability change during actual molding process brings up difficulty in achieving consistency in part quality. This article presents an adaptive RTM injection design approach in which process simulation and Hardware-In-the-Loop-Simulation (HILS) technique are used: the whole-field preform permeability profile is provided by an in situ gas-assisted permeability measurement system and then inputted to the process simulation right before each control step during molding; an open loop control method steering the resin flow is also proposed. It is found that the HILS can be used to realize optimal injection design and flow control with accurate online permeability estimation.