Laboratory experiments are performed for staple fibre -nonwoven geotextiles which have been widely used in Korea to investigate the filter characteristics of soil/geoteztile system under alternating flow conditions. It is experimentally examined the effects of various design factors such as alternating hydraulic gradient, alternating period, vertical load, gradation and density of foundation soil on the filter structure, vertical permeability and soil retention of soil/geoteztile systems. Based on the experimental results, alternating flow filtration criteria- retention criteria and permeability criteria-for staple fibre-nonwoven geotextiles made in Korea are suggested.