Abstract: Odor problems in leather-making processes have received more and more attention with increasing environmental awareness among the populace. However, there is currently a lack of systematic research and a summary on the sources, causes, and control methods of odor from the leather-making processes. A three-round Delphi survey was conducted to study the odor levels and sources of the leather-making processes by consulting 51 experts from leather-making enterprises, industry associations, and universities in the leather field. Results show that the odor in the leather-making processes mainly comes from seven procedures and the odor levels of these procedures, from high to low, are storage, unhairing, liming, soaking, fleshing, deliming, and splitting. The main odorous substances are odorous gases generated by decaying hides or hide scraps in the rawhide warehouse, fleshing and splitting machines, and ground gaps; odor of industrial sulfide impurities; and ammonia and hydrogen sulfide released from ammonium salt deliming. It is recommended that tanneries prevent and control odor pollution by inhibiting rawhide decay; keeping fleshing machine, splitting machine, and tannery ground clean; adopting low-sulfide hair-save unhairing and ammonia free deliming technologies; and spraying deodorants.