Abstract: A special apparatus was constructed by modifying capillary rheometer to study polymer melt flow behavior through fiber beds. One dimension constant pressure flow experiments were carried out to measure the transverse permeability of two glass fiber mats in both unsaturated and saturated flow using PP melt as permeant. The effect of mat architecture on permeability was investigated including mat porosity, fiber diameter and needles. Furthermore, selection of impregnation parameters in GMT melt impregnation was discussed according to the experimental results.