Abstract: Manufacturing technology of complex amino acids fertilizer chelated with microelements,such as iron(II),zinc,manganese,and copper was studied in this paper.Amino acids were hydrolyzed from waste chicken feather.Highly pure solid chelates of amino acids with iron(II),zinc,manganese,copper were separated using precipitation fractionation by adding organic solvent.The optimum manufacture conditions for chelates synthesis were evaluated based on the chelation rate.The optimal molar ratio of ligand of the amino acids to the four microelements was 2∶1 and pH for the chelation with iron(II),zinc,manganese and copper were 5.0,8.0,4.05.0,and 6.07.0,respectively.Chelation could take place at room temperature(2226℃) for 30 min.All the chelation rates of amino acid with the four microelements were more than 95%,under above conditions.The results also showed that these four chelated salts could be blended with 0.2 mol/L potassium dihydrogen phosphate(KH2PO4)(quality concentration 2.72%),therefore,it partly solves the problem that traditional microelements fertilizer could not re-blend with phosphate.