Polyethylene glycol 1500 was used as raw material to synthesize bisazide polyethylene glycol (N3-PEG-N3) intermediate by two-step functional group transformation. One side of the N3-PEG-N3 was reduced by organic phase and terminated by aqueous phase to achieve unilateral reduction of azide. Reaction selectivity was evaluated by liquid chromatography-mass spectrometry (LC-MS) and the content of excimer ion peaks of each component. The reduction rate of azide group on one side reached 97%. The optimum liquid-liquid two phase reaction conditions of amino azide polyethylene glycol (NH2-PEG1500-N3) were determined by single factor experiments: the molar ratio of bisazide polyethylene glycol to tri-phenylphosphine oxide was 1:1.1, the organic phase was toluene and dichloromethane as mixed solvent (3:2), aqueous phase was 2 mol/L hydrochloric acid solution, and the ratio of the two phases was 1:1, reaction at 35 oC for 12 hours, and then NH2-PEG-N3 was purified by column separation, yield is 72%. The results show that this method is simple and high purity. The products were characterized via 1H-NMR and HRMS. Finally, the hetero-polyethylene glycol was used to synthesize azide-terminated functional phos-pholipids.