Diphenyl-2-ethanolamidophosphate (DPEOAP) was synthesized to treat polyester fabrics in order to improve its flame retardancy. The flame retardancy and physical properties of DPEOAP-treated polyester fabrics were investigated. The results were as follows: 1) polyester fabrics can be treated with DPEOAP by means of Pad-Dry-Cure method, because DPEOAP was easily soluble in benzene. 2) The most economic conditions of treatment were determined as 10% of DPEOAP cocentration, 140℃ of curing temperature, and 2 minutes of curing time. 3) Though the washablity of DPEOAP is low in comparison with the other products which are purchasable in a market, it has an excellent flame retardment effect 3 times more than in number of flame contact just with 0.66% add-on. 4) The physical properties of DPEOAR treated polyester fabrics were little changed as compared with non-treated fabric.