Phosphorous fractionation is a method developed to estimate sizes of readily soil available P pool,and soil P sub pools and their ability to replenish the available P pool.Three types of acid soil (laterite red soil,yellow red soil and brown red soil),of which the first two were sampled from Yunnan Province and the third one was sampled from Hubei Province,were used in pot experiment under a rain shelter condition to investigate the effect of lime amendment on P fractions and their bioavailability by plant of broad bean.A new phosphorus fractionation scheme was developed and used to study P bioavailability in the tested soils compared with the two typical soil P fractionation schemes,Chang Jackson on acid soil and Jiang Gu on calcareous soils.The new phosphorus fractionation scheme used a series of sequential extractants,such as 0.25 mol L^-1 NaHCO₃,1 h (for Ca₂-P),0.5 mol L^-1 NH₄F (pH8.5),1 h (for Al-P),0.7 mol L^-1 NaClO,pH 8.05,85 & water bath 30 min (for Org-P),0.1 mol L^-1 NaOH 0.1Na₂CO₃,4 h (for Fe-P),1 mol L^-1 NaOH,85 & water bath.h (for O-Al-P),0.3 mol L^-1 Na citrate 0.5 g Na₂S₂O₄-0.5 mol L^-1 NaOH,80 & water bath 15 min (for O-Fe-P),0.25 mol L^-1 H₂SO₄,1 h (for Ca₁₀ P),Results showed that Ca₂ P,Al-P and Fe-P were the main available P sources in acid soils.O-P was potentially available phosphorus source,which could be subdivided into O-Al-P and O-Fe-P with the new phosphorus fractionation scheme,and the latter reflected difference be tween CK and lime treatment in plant availability.The size of the labile organic fraction was relat ively invariable and could be transformed into a highly available P source to plant.Further study may be needed on extractant for labile organic phosphorus in determining soil P availability in acid soils.