In this study, the extracting experiment was conducted to investigate the effect of EDTA and citric acid (pH=4) on P mobilizationin in the grain field soil, greenhouse soil and P-stabilized greenhouse soils under different concentrations (0, 0.05, 0.1, 0.25, 0.5, 1.0 g/L) and different extraction times (1, 12, 24, 48, 72 h), to make sure the optimal concentration and extraction time of chelating agent to extracts P from soils. The results indicated that the optimal concentration and extraction time were 0.05 g/L and 12 h for EDTA and citric acid in grain field soil. The optimal concentration and extraction time were 0.5 g/L and 12 h for EDTA and citric acid in green house soil, alum-stabilized soil and mixed-stabilized (alum:dolomite was 1:1) soil. The optimal concentration and extraction time were 0.5 g/L and 1 h for EDTA and citric acid in dolomite-stabilized soil. Generally, the effect of citric acid was better than that of EDTA, especially in alum and dolomite stabilized soil.