Pasteurized egg white was used as raw material and modified by sodium tripolyphosphate (STP). The optimum conditions for the phosphorylation of egg white were determined by single factor and orthogonal test, for the reaction pH 7.5, the amount of STP 4%, the reaction temperature 40 ℃, and the reaction time 4 h. Under the optimal conditions, the degree of phosphoryl-ation reached 50.96 mg/g. The low-field nuclear magnetic resonance (LF-NMR) was used to observe the binding of proteins to water during the process. The results showed that the solubility, water - holding capacity, foaming property and emulsifying property of egg albumin were all improved after phosphorylation.