The exchange of phosphorus across sediment-water interface of Lake Xuanwu under static state was studied in laboratory,and effect factors of phosphorus exchange across sediment-water interface were carried out under 100%,75%,50%,25% and 0% saturation dissolved oxygen concentration. The results showed that the relationship between dissolved total phosphorus and dissolved phosphorus release rate from sediment with dissolved oxygen concentration in overlay water was parabola. The direction of phos-phorus exchange across sediment-water interface was decided by the dissolved oxygen. The maximum pervasion depth in pore water under different dissolved oxygen concentration influenced the phosphorus exchange amounts across sediment-water interface. Dis-solved oxygen affect directly the electric potentials and algae absorbing phosphorus and pH value, then influenced the phosphorus exchange across sediment-water interface.