The three- dimensional seepage simulation test device for siltation dam foundation soil is a multifunc- tional penetration instrument which is designed for the simulation of infiltration clogging，seepage damage，and dam seepage and so on． This device is different from the traditional instruments for the rock and soil permeabili- ty． In order to verify the practicability of the device，the authors collected the soil samples for laboratory pene- tration test，observed the seepage damage phenomenon，and obtained the dynamic change curve of permeability coefficient and isopotential map of water pressure． At the same time，the Geostudio finite element software is used to simulate the steady seepage of the test device． By contrast of the isopotential maps between simulation and actual water pressures， it is found that they are approximately the same． It is proved that the test data of the device is scientific and reliable，reaching the results of the test and design purposes． The instrument can be used in many aspects of experimental study on soil seepage．