Improvement of saline soils is very important from the point of view of soil and water resources conservation. Excess Solution salts in the root zone can reduce water uptake by the plant due to reduced soil osmotic potential. Necessary strategy in dealing with this issue is reducing the soil salinity to optimum level by capital leaching. The purpose of this study was to investigate the application of different amounts of leaching water in reducing salinity and evaluating experimental and theoretical models in predicting final salinity. This research was carried out in a part of Mohammadabad lands of Sistan plain as a randomized complete block. This experiment are carried out with five treatments and four iterations using test plots with one-to-one meter. Leaching was performed using 100 cm of water in four intervals of 25 cm. The required physical and chemical analyses before and after leaching and after the application of each irrigation cycle in treatments and at different depths up to 100 cm of soil were performed on the collected data. The results showed that the use of 100 cm of water for leaching could reduce the soil salinity class from S2A2 to S1A2. Experimental and theoretical models were evaluated and the results showed that theoretical models predicted the final salinity better than experimental models. Of all the experimental and theoretical models studied in this study, the theoretical model of a single reservoir with a correlation coefficient of 94% had the best results.