In view of the practical problems of large quantities and high production cost in the existing heavy saline alkali land improvement measures, taking the large-scale heavy saline alkali land interlayer soil formed after the large-scale, efficient and water-saving construction of Weigan River irrigation area as the research object, through the field plot test, the soil water and salt change law of different measures under winter irrigation conditions is studied. Analysis shows that all treatments, except for G1 treatment, have the highest soil moisture content at the interlayer position of 60 cm to 80 cm before and after irrigation. After three rounds of irrigation, the soil moisture content of CK treatment at 60 cm to 80 cm is 1.4% to 16.2% higher than other treatments, and the average soil moisture content at 0-100 cm is 2.3% to 15.5% higher than other treatments. At the same time, CK treatment had the highest salt content in the soil between 60 cm and 80 cm, and the desalination rate was low. After three rounds of irrigation, the desalination rate was 24.9%, only higher than G4 treatment (14.9%). Among all measures, G1 treatment had the highest desalination rate at 75.9%, followed by G6 and G3 treatments at 51.5% and 39.4%, respectively. G2 and G5 were relatively close at 38.2% and 37.4%, respectively. G4 had the lowest desalination rate at 33.9%. After two and three winter irrigations, the desalination effect of each treatment was significant, especially in the 0-20 cm soil layer, which decreased from 7.06 g/kg to 11.61 g/kg before irrigation in 2020 to 2.0 g/kg to 5.91 g/kg after irrigation in 2022. The desalination rate was between 76.8% and 382.5%, which improved the surface soil from the initial medium to moderate saline alkali soil to light to moderate saline alkali soil. The relationship between the increase in salt content and the increase in water content was inversely proportional, The research results not only reflect the blocking effect of clay interlayer on water and salt transport, but also indicate that improvement measures can promote soil water infiltration and improve soil desalination efficiency, providing data support for the selection of soil improvement measures in heavy saline alkali soil interlayer.