Abstract: Planting paddy rice is an important and effective way to improve saline-sodic soil.Aiming to find out the changes of phosphorus nutrients content and salinity characteristics in soil with the years of cultivation,and to reveal the obstacle mechanism of soil salinity on phosphorus nutrient promotion,we analyzed the changes of soil salinity and phosphorus content by collecting soil samples from different cultivation years at Da'an station.The results showed that soil pH,EC and SAR increased under different cultivation years,while the total phosphorus and available phosphorus content decreased significantly with the increase in soil depth (P<0.05).With the increase of rice planting years,the surface soil pH,EC and SAR decreased significantly,and the total phosphorus and available phosphorus content increased significantly (P<0.05).However,the changes of soil pH,EC,SAR,total phosphorus and available phosphorus content were not significant below 40 cm soil depth.The stepwise regression analysis and correlation analysis showed that soil pH was the main limiting factor for the increase of soil total phosphorus (R²=0.649,P<0.001),and soil EC was the main limiting factor for the increase of soil available phosphorus (R²=0.5126,P<0.001).Therefore,the changes of soil salt,alkali and phosphorus content in saline-sodic paddy field were in a slow process.In order to improve soil fertility in an all-round way,it would be necessary to reduce salt and alkali rapidly through soil improvement.