The invention provides a method for preparing high-purity fosinopril sodium. Crude fosinopril sodium is first acidified, a phosphate solvent is then used as an extracting liquor for extraction, all organic phases are collected, an alkaline solution of sodium is then used for alkalization, and after filtration and washing, pure fosinopril sodium is obtained. Compared with the prior art, the methodhas the advantages of simplicity, high product yield and purity, suitability for industrial production and the like.