Objective To systematically evaluate the nutritional characteristics of amino acid of quinoa lines with different grain colors.Method The composition of amino acid was determined by high-performance liquid chromatography， and the nutritional value was assessed using the FAO ideal model combined with the amino acid ratio coefficient method.Result Seventeen amino acids were detected in all tested quinoa lines， including seven essential amino acids. The total amino acid content of black quinoa was significantly higher than that of the red and white lines （P<0.05）.The average percentage of essential amino acids in the three grain colors of quinoa was 34.4%. The medicinal amino acid content was 71.9%. Black quinoa had the highest amino acid ratio coefficient score （SRCAA） and essential amino acid index value （EAAI） of 92.88 and 1.15， respectively， which were close to the FAO recommended threshold.Conclusion Quinoa of different grain colors has excellent nutritional value， especially black quinoa， and valine is the first limiting amino acid of quinoa.