The unique physical properties of leather make it ideally suited for the manufacture of a variety of products. Retanning has important effects on the mechanical and physical properties of the resultant leather. In this paper, a novel amphoteric acrylic copolymer as retanning material was prepared by free radical copolymerization. The effects of this copolymer on the physical properties of the resultant leather have been investigated by measuring physical and mechanical indexes of the retanned leather. The function mechanism of this copolymer was also researched. Results showed that this copolymer could improve the properties of the resultant leather including softness and strength, and increase leather’s dyeability in contrast to anionic acrylic polymer.