The environmental impact of phosphorus on surface water quality by a long-term applying fertilizer P in the upland fields of yellow soil areas and its risks evaluation was studied in Guizhou province.The results showed that the contents of algae-available P (NaOH-extractable P) and labile P (CaCl₂-extractable P) in the soils correlated significantly with the quantities of Olsen-P or total P in the soils, while P application increased both soil P and its corresponding potential of P loss from soil to water bodies at the same time.The results also showed that the contents of CaCl₂-extractable P, Olsen-P, NaOH-extractable P in the soils and the phosphorus sorption of index (PSI) or the degree of soil saturation with phosphorus (DSSP) correlated significantly with the concentrations of dissolved active P, particulate P and bioavailable P in runoff, respectively.CaCl₂-extractable P, Olsen-P, NaOH-extractable P, PSI and DSSP were used as indices to estimate agriculture P impacting on surface water quality.As a result, three environmental risk groups were constructed in the upland fields from yellow soil area.