Abstract: The compressibility of fabric preforms in vacuum infusion molding process (VIMP) was studied by loading vacuum pressure. The effects of cyclic loading, fabric form, fiber type, number of layers, way of layup and hybrid mode on the compressibility were investigated. The results show that the fiber volume fraction increases with the times of cyclic loading, while the growth value decreases. The growth value of fiber volume fraction slightly increases with the number of layers under the same vacuum pressure that it almost can be neglected in vacuum infusion molding process(VIMP). The way of layup, fabric form, fiber type and hybrid mode have remarkable effects on the compressibility of fabric preforms. The undirectional layup results in a higher fiber volume fraction than the orthogonal layup under the same compaction pressure, and the higher fiber volume faction can be achieved in the core hybrid composite compared with that in the interply hybrid composite.