The permeability tensor of fiber reinforcement

as the decisive input parameter of resin flow simulation of liquid composite molding process

is closely related to the resin flow and final product quality

and is the key to realize the high-quality and large-scale manufacturing of composite materials. In this paper

the permeability measurement techniques are classified according to the flow states (saturated or unsaturated)

flow dimensions and measurement directions (in-plane or out-of-plane). The permeability measurement techniques and research progress under different conditions are listed

and the real-time monitoring techniques of flow front in unsaturated flow are summarized. The problems such as different experimental factors and large dispersion of permeability results are analyzed

and the future development trends are discussed.