In order to explore the correlation between phosphorus and iron in the sediment-water interface, by the indoor cultivation of situ sediment column, this study used the micro interface analysis technology and the interstitial water collection technology of high resolution balance type(HR - Peeper), and designed three stages(7, 21 and 35 days after adding the Chironomus larva), to explore the transfer mechanism of phosphorus in the sediment-water interface system under the oxidative coupling of Chironomus larva disturbance and iron in aerobic environment. The results show: the disturbance of Chironomus larva increased the penetration depth and E_h of oxygen in sediments, and the disturbance was most intense on the 21st day; the disturbance reduced the concentration of Solubility Reactive Phosphorus(SRP)with maximum 58% and Soluble Fe(Ⅱ)with maximum 44% in the interstitial water of three stages; SRP and Soluble Fe(Ⅱ)were also highly correlated on days 7 and 21. It can be seen that the change of P in the sediment caused by the disturbing action of Chironomus larva is controlled by the oxidation adsorption of Fe.