The amount of particulate phosphorus and dissolved phosphorus loss in runoff from yellow soil of hilly areas by de farming reafforestation in Guizhou province were studied. Results showed that the contents of particulate P and ortho P respectively reduced 22.17%~63.48% and 3.03%~44.29% in surface runoff derived from de farming reafforestation lands than in that from farming lands and that the amount of particulate P loss in runoff decreased 35.08% or 41.94% from plots de farming and reafforestation the slope than from plots cultivated the slope, while the amount of dissolved P loss also reduced 38.65% or 53.42%. Therefore, de farming and reafforestation were an effective way to reduce phosphorus loss in the upland fields due to decrease the amount of phosphorus putting in the soils or putting out form the soils.