The hydraulic permeability performance of geosynthetics is an important functional technical index in the field of engineering application. In this paper, the pore size characteristics of a series different specifications of spunbond and needlepunched nonwoven geotextile has tested through capillary flow aperture measuring instrument, including average pore diameter, maximum pore size and pore size distribution. The permeability characteristics of nonwoven geotextile has measured by vertical permeability measuring instrument, including flow index and vertical permeability coefficient. We study on the compressive properties of nonwoven geotextile under the different pressure, through the relationship between the average pore diameter and flow index to fit curve, and built the regression equation, so we can calculate and predict the water permeability performance through pore size Characteristics.