Abstract:The purpose of this study is to analyze the effect of biochar compounded with flocculated yellow river sediment on the water and salt transport and hydraulic characteristic parameters of saline soil through the laboratory tests with ring-knife. Firstly, biochar and flocculated Yellow River sediment were mixed into soil improver at the mass ratio of 4∶6, and then the soil improver was mixed into saline soil as the proportion of 0, 1%, 2%, 3%, 6%,and 10%. The results showed that: (1) Soil porosity and water content increased with the increase of soil improver.The soil porosity and water content under the 10% level are average increased 12% than the control treatment. (2) The saturated hydraulic conductivity of soil reaches the maximum at 3% addition, which is 68.9% higher than that control. (3) The additional amount of soil improver is inversely proportional to the rate of water diffusion, so that the soil pH value is higher, and then have the small effect of salt leaching.It was found that the decrease of soil salt was more obvious when the content of 3% was added. The amount of salt reduction above 17 cm reaches 30%~50%, but the increase in soil pH is only about 4%. The Boltzmann parameter λ increased by 31.5%, and the water diffusion rate was faster. All things considered, applying 3% soil improver can effectively increase soil porosity, soil water content, saturated hydraulic conductivity, water diffusivity, and reduce the soil salinity on the surface.