Abstract: Aiming to develop the process ability of liquid molding on two kinds of unidirectional fabric, compressibility and permeability tests were carried out on preform by two types of unidirectional fabric made of domestic CCF300 carbon fibers-plain unidirectional fabric U3160 and uniaxial non-crimp fabric KUC160. Two types of unidirectional fabric/bismaleimide resin composites were fabricated with resin transfer molding (RTM) processes, and in-plane mechanical properties of the composites were investigated and compared. It is found that the nesting effect during the preform compression test is influenced by the pressure and number of the fabric layers. The nesting effect is increased with the increase of pressure and the number of the layer. U3160 fabric displays more noticeable nesting effect than that of KUC160 fabric. Hence, the fiber volume fraction of KUC160 fabric preforms is about 20% lower than that of U3160 fabric preforms under high pressure. The permeability test results show that KUC160 has a higher permeability along the 0° direction than that of U3160 fabric, while the permeability perpendicular to the fibers of KUC160 fabric is lower than that of U3160 fabric. It may be attributed to that the binding effect of stitching yarns enhances the macro-flowing along the 0° direction, but weakens the micro-infiltration perpendicular to the fiber direction. In addition, the stitching yarns of KUC160 and the stabilizing yarns of U3160 have flow guiding effect on the permeability. Mechanical property test results show that compared with composites reinforced by U3160, the tensile, flexural and compressive properties along the 0° direction of KUC160 reinforced composites decrease. To be specific, tensile strength and flexural modulus decrease the most by 11% and 21%, respectively. The interlaminar shear strength slightly increases by about 8%.