Abstract: The permeability coefficient is one of the key parameters for studying the actual engineering water seepage problem. In the past, in the experimental study on the permeability coefficient of unsaturated soil, the humidification condition was relatively simple, and the influence of vertical additional stress was rarely considered. Based on this, a one-dimensional vertical soil column test device was developed to compensate for this defect. The device is mainly composed of test bench, soil column cylinder, vertical loading device, water supply device, moisture sensor, tension sensor and data acquisition system, which can simulate the test conditions of rainfall, water infiltration and capillary rise under vertical-additional-pressure, and measure the infiltration quantity and wetting front time-history curve, the vertical deformation of soil column, the volumetric moisture content of different sections and the time-history curve of matric suction. Based on transient profile method, when the humidifying the relation between unsaturated permeability coefficient and suction at different sections can be obtained. Finally, taking Lanzhou Q3 unsaturated silty loess as an example, preliminary experiments on soil water infiltration under different vertical additional stresses were carried out to analyze the infiltration, wetting front, volumetric water content, suction and vertical deformation time history. The variation law of the line, the change law of the permeability function of the relationship between the permeability coefficient and the suction force is obtained. By comparing the similar test results, the test results are consistent with the water seepage law, and the effectiveness of the soil column instrument is verified. However, the reliability needs further study. The test device lays a foundation for studying the characteristics of deformation, water migration and permeability of unsaturated soil under different working conditions, and obtains corresponding test parameters.