Due to the excessive application of phosphate fertilizer，phosphorus is accumulated in the soil，and there is a potential risk of the environmental pollution.In this study，by comparing the changes of available phosphorus content in the cultivated layer of Yanqi basin in 1980，2010 and 2020，the spatial and temporal enrichment characteristics of soil available phosphorus were analyzed，and the environmental risk was analyzed by using the relative ecological risk coefficient. The results showed that from 1980 to 2020，the available phosphorus in Yanqi basin increased from low to abundant level，and available phosphorus increased 2.66 times with an annual increase of 0.62 mg/kg.Bohu county had the highest annual increase of 0.96 mg/kg.Through the spatial interpolation analysis，the available phosphorus content of the cultivated soil in Yanqi basin was mainly moderate in 1980，it was relatively rich in 2010，and it was abundant in 2020，and the available phosphorus content of newly reclaimed land was also rich.The available phosphorus content in Bohu county，Hejing county，and Yanqi Hui autonomous county was enriched.According to the relative ecological risk coefficient of phosphorus in 2020，the environmental ecological risk area of available phosphorus was obtained by spatial interpolation analysis of Arc GIS.The part of the cultivated land in Yanqi basin had potential ecological risk，and its area was 1811.45 km2，accounting for 64.34% of the cultivated land.The main risk types were medium and low ecological risks，and the area of high risk was small，accounting for only 0.01% of the study area.The area with potential risk of available phosphorus was as follows:Hejing county> Yanqi Hui autonomous county> Bohu county> Heshuo county.Therefore，according to the characteristics of available phosphorus enrichment of Yanqi basin，the regional nutrient management strategy should be adopted to reduce the risk of non-point source pollution，so as to reduce phosphorus and increase efficiency to promote environmental protection.