The spatial variation and the driving factors of soil available phosphorus (AP) of farmlands in Xinguo County under different erosion levels were analyzed by using the methods of Spearman correlation analysis, regression analysis and ordinary kriging combined with elevation, slope, parent material, soil texture, topsoil thickness and landform type. The results showed that the average AP decreased first and then increased with the increase of soil erosion level. Significant differences were found between AP under different soil erosion degrees (P<0.001), the coefficient of variation decreased in the order as extremely intensive erosion (35.20%) > severe erosion (28.09%) > slight erosion (28.02%) > serious erosion (27.90%) > unobvious erosion (25.96%) > moderate erosion (25.78%). In the case of unobvious erosion, parent material could explain 1.7% of spatial variability of AP. In the cases of slight, moderate and serious erosion, elevation could explain 5.7%, 2.3% and 2.9% of spatial variability of AP, respectively. In the case of the extremely intensive erosion, parent material could explain 5.0% of the spatial variability characteristics of AP. In the case of severe erosion, elevation could explain 1.9% of the spatial variability characteristics of AP. Thus, parent material and elevation are the main driving factors in controlling the spatial distribution of AP. The study results could provide references for the rational use of farmlands and for soil and water conservation under different erosion degrees.