The problem for the removal of phosphorus increased due to reasons like eutrophication control. However its removal and operating criteria were not well developed. This study was made for enhanced removal of P by iron contactor by intermittent aeration activated sludge process. Experiment was conducted to find the effects of organic substance load and HRT, nutrient removal efficiency. When applied organic substance load and HRT, II &III reactor were good treatment efficient while come from Fe of iron contactor. Release of phophorus from II &III reactor sludge under anaerobic condition was low. As the process developed, the content of released ionized Fe from iron contactor increased. In addition, the rate of phosphorus removal became accelerating, and the removed sludge was stabilized in the existence of insoluble status.