The invention relates to the technical field of water treatment, in particular to a preparation method and application of metallurgical carbonate hydrotalcite. The preparation method includes subjecting metallurgical waste residues to nitric acid acidolysis, adjusting the pH of acidolysis filtrate, adding sodium dodecyl benzene sulfonate and polyacrylamide aqueous solutions to remove iron, and subjecting the filtrate and sodium hydroxide/sodium carbonate solutions to double titration to obtain the hydrotalcite. The preparation method has the advantages that the metallurgical waste residues areeffectively utilized to synthesize other materials and recover iron that can be reused in metallurgy, and the recovery efficiency of the iron is improved.