Abstract: Slotted pipe drainage system plays an important role in reducing the wetting line of tailings dam.Previous studies have mostly determined the permeability coefficient of geotextiles based on one-dimensional test.The permeability characteristics of the whole system of slotted pipe outer geotextiles are less studied.A set of radial flow test equipment for the geomembrane drainage system of the slotted tube is designed and developed.Based on the experimental equipment developed by the research and development, the seepage experiments of the slot pipe drainage system under different head differences and different geotextile layers are carried out to study the influence of the number of geotextile layers and the head differences on the permeability characteristics of the drainage system.The experimental results show that with the increase of water head differences, the permeability coefficient of the slotted pipe drainage system has a gradually increasing law; as the outer geotextile is increased from one layer to the second layer, the permeability coefficient is significantly reduced, but the number of geotextile layers continues.Increased permeability coefficient and a slight increase.The experimental results in this paper can provide a reference for the application of the overall structure of the slotted tube geotextile in the drainage and seepage of the tailings dam.