Abstract: In order to accurately calculate the osmotic suction in saturated saline soils under different salt contents, salt types and temperature conditions, firstly, a brief review is made of the research results of osmotic suction from the test and theoretical aspects. Secondly, through the electrical conductivity tests on sodium chloride and sodium sulfate solution under different temperature conditions, the relationship between the soil osmotic suction and the concentration after saturation of the two solutions is discussed. Finally, based on the fractal theory and solute ionization degree, the EC model and van't Hoff equation are improved, respectively, and the improved model is analyzed numerically. The test results show that the osmotic suction of the soil after sodium chloride saturation has an increase of power function with the concentration, while the osmotic suction of the soil after sodium sulphate exponentially increases with concentration. Therefore, the osmotic suction of sulphate saline soil is higher than that of chlorine saline soil at first, while that of chlorine saline soil is higher than that of sulphate saline soil after a certain concentration, and the concentration value m_A of intersection point A increases linearly with the increase of temperature. The numerical analysis results show that the improved model can calculate the osmotic suction under complex conditions and is superior to the traditional models.