Researches on the 0—20 cm surface soil in a long-term experiment of soil and fertilizer at the First Station of Agricultural Cultivation of Northwest University of Agricultural and Forestry showed that easily released phosphorus of various fractions had a close positive correlation with total phosphorus(TP).The ability of soil releasing phosphorus reduced as pH increased,and the buffer capacity differed in different treatments.The releasing ability was also related to TP.Total phosphorus of surface soil had a significantly positive relation with PSD.So,the PSD of 25% of the soil was considerated to be a predicting index,and TP of 1.92g/kg could be used as sensitive environmental index which would predicted phosphate leaching in Guanzhong Plain soil.