A flame retardant named as ethyl neopentyl phosphate was synthesized with neopentyl glycol, phosphorus ox-ychloride and ethanol as raw materials. The chemical structure of ethyl neopentyl phosphate was identified by means of FTIR, 1HNMR, 13CNMR, 31PNMR and ESI-MS. The effects of material ratio, reaction time and reaction temperature on the reaction were studied. The results show that the optimum conditions are (neopentyl glycol chlorophosphate):n (ethanol) = 1.0:5.0, the reaction temperature is 50℃, the reaction time is 8 h and the yield of the obtained product can reach 80.8%. Ethyl neopentyl phosphate was then applied in rigid polyurethane foams (RPUF), and the flame retardancy of the resulting composite material was determined by limiting oxygen index (LOI) measurements and vertical (UL-94) tests. Meanwhile, the thermal stability of flame retardant and RPUF was characterized by thermogravimetric analysis (TGA). The results indicated that the addition of ethyl neopentyl phosphate reduced the thermal stability to a certain extent, but improved the flame retardancy of RPUF. the composite containing 30% ethyl neopentyl phosphate could achieve UL-94 V-2 rating with a LOI value of 22.5. %, higher than that of pure RPUF(17.1%), and the residual mass increased from 15.8% ( for pure RPUF) to 18.9%.