Collagen is an important essential tissue protein in creatures with excellent biocompatibility, biodegradability and biological activity. The origin and types of collagen are comprehensive. However, the application of unmodified collagen is not satisfactory. This was attributed to poor physical and chemical properties such as thermal stability, mechanical strength, and enzyme resistance. Hence, improving collagen properties via modification attracts attention of researchers. Amino groups on the side chain of collagen provide strong crosslinking ability and positive charge. The application of collagen can be further expanded by amination, which related to the enhancement of positive sites and surface charge of collagen. In this background, the properties and main modification methods of collagen are introduced detailly. The latest research progress of amino-modified collagen in biomedicine, environmental management and the leather industry is reviewed. Finally, the future development of amino-modified collagen in a clean chrome-free leather tanning system has also been prospected.