Effects of phytase on phosphorus release under the influence of exogenous oxalic acid were studied using lab synthesis method and the Hedley sequential phosphorus fractionation scheme.The results showed that the treatment of applied in oxalic acid and phytase together could improve the soil effective phosphorus content，significantly higher than the contrast processing treatment of blank，oxalic acid and phytase.From the various components of phosphorus，the treatment of applied in oxalic acid and phytase together could increase the amounts of H2O P，NaHCO3 Pi，NaOH Pi and NaOH Po and they reached the highest in the 40th day，with the extension of incubation time rising，which higher than blank control 37.76%，21.14%，15.52%，24.44%；Labile phosphorus amounts except NaHCO3 Pi of the treatment of applied in oxalic acid and phytase together were higher than the treatment of phytase；The amounts of HCl P and Residual P of the treatment contain phytase were lower than those of blank and oxalic acid treatment，and with the extension of incubation time its amount decline，which stabilized in the 40th day.At this time，the amounts of the treatment of applied in oxalic acid and phytase together was lower 28.71% and 32.56% than before.Conclusion，under the influence of exogenous oxalic acid，phytase could make the labile phosphorus component into stable components，so as to improve the utilization ratio of phosphorus.