Low phosphate availability is one of the major limitations to crop production.Organic acids are a principal component of root exudates and have been hypothesized by many authors to be involved in the mobilization of nutrients within the rhizosphere.Mobilization of insoluble phosphates by root exudates plays an important role in improving P nutrition of crops.The effect of different phosphorus level on dynamic of available phophorus in soils had been studied.At the same time,two maize inbred lines with different tolerance to low-P stress were grown for 15 days in nutrient solution with different phosphorus treatment.The root exudates were collected and added into the three types of soil which had incubated for 95 days.The results showed that the available phosphorus content quickly increased by application of different phsphate,and then constantly decreased by time,and were steady after 60 day;and the available phosphorus from acid soil is significant lower than alkali soil and neutral soil.The soil available phosphorus content was extracted by the root exudates of M02 collected under low phosphorus condition significant pronounced with the addition of insoluble phosphate to the deionized soil;and AlPO4 mobilization by root exudates was significantly higher than Ca3(PO4)2.