Collagen is an excellent biomaterial. Biological characteristics of collagen including biodegradability and weak antigenicity made it a primary resource in medical application. In biomedical field collagen is mainly used as sponges for wound/burn, supplement in rheumatoid arthritis, drug delivery system, controlling material for transdermal delivery and basic matrices for cell culture system due to its ability to stimulate formation of tissue and organ. Moreover, collagen is also applied in tissue engineering including bone defect, tissue regeneration, skin replacement and artificial blood vessels and valves. The article reviews biomedical application of collagen in wound healing, rheumatoid arthritis, drug delivery system, tissue engineering and lung function improvement in pulmonary fibrosis due to viral infection.