In this study, experimental test equipment developed in-house was used to study the compaction behavior of stitched quasi-unidirectional (UD) non-crimp fabrics (NCF) during the pre-filling, filling, and post-filling stages of the vacuum infusion (VI) process. The effects of the stitch pattern, stitch tension, and fiber sizing of reinforcements, as well as the effect of nesting of fiber bundles in neighboring layers, were studied. Moreover, the effects of cyclic compaction, resin viscosity, and different post-filling strategies were studied. The developed experimental test equipment provided an applicable measuring method for characterizing the compaction behavior of both the dry and resin-impregnated reinforcements. The effects of the stitching parameters and fiber nesting of reinforcements were found. The stitch pattern and post-filling strategies were noted to have an effect on the preform and laminate thickness. POLYM. COMPOS., 37:2692–2704, 2016.