[Objective] Through the treatment of hydrophilic and hydrophobic by the conditioner, the influence of different interface characteristics of the conditioner on the soil water and salt transport law was explored, and the improvement mechanism of fly ash-based soil conditioner on saline-alkali land was revealed in order to provide scientific reference for the improvement of different types of saline-alkali land in irrigation area of the Yellow River. [Methods] Taking sodic sline soil in Ningxi Hui Autonomous Region as a case study, the spatial transport patterns of different salt ions in the soil before and after modification with the soil conditioners were investigated by soil column experiments. [Results] After the addition of unmodified conditioner, hydrophilic-modified conditioner, and hydrophobic-modified conditioner, the surface desalination rates were 79.72%, 59.91%, and 84.79%, respectively, for a sodic saline soil far greater than the values obtained without conditioner added (12.64%). Compared with the unmodified conditioner treatment group, the water content of the hydrophilic treatment group was 6.59% greater, and the total salt amount was 47.13% greater. The water content of the hydrophobic treatment group was 0.67% less, and the total salt amount was 25.22% less. The pH values were reduced from 10.5 to 8.08 and 8.71, respectively. The surface Na⁺ contents were reduced by 10.39% and 30.46%, and the K⁺ contents were reduced by 10.22% and 45.93%, respectively. [Conclusion] The interface properties of soil conditioners significantly affected water and salt transport in the soil. The hydrophobic conditioner treatment was more effective in improving saline land, and increasing the infiltration of salts with soil water is more important for saline land improvement.