Abstract: The large amount of ammonium salts used in the conventional deliming process is the main source of ammonia nitrogen (NH₃-N) pollution in the leather manufacture. Replacing the ammonium salts with ammonia-free deliming agents for the deliming is an effective way to eliminate the NH₃-N pollution from the source. However, the existing ammonia-free deliming agents have inadequate pH buffering capacity, slow penetration, high cost, or toxicity. The bovine hair waste and hide scraps from the leather-making processes were used as raw materials to prepare compound amino acids for clean deliming. The deliming agents with amino acid content of approximately 40% were obtained by optimizing sulfuric acid-hydrolyzing conditions. The obtained deliming agents were then used to delime limed cattle hides. Results showed that the compound amino acids formed a buffer of pH approximately 9 after reacting with the alkali in the limed hide, penetrated the hide rapidly, and removed the lime from the hide effectively. The concentrations of NH₃-N and total nitrogen in the deliming effluents by using the compound amino acids were decreased by more than 94% and 64%, respectively, compared to those of ammonium sulfate deliming effluent.