The collagen was extracted by acid, enzymolysis and hot water methods respectively from the body wall of Sipunculus nudus, and their physicochemical properties were analyzed. The three collagen extracts were compared respectively by amino acid composition, UV spectroscopy, Fourier infrared spectroscopy and SEM scanning electron microscopy. The effects of the three collagen zynolytes on the growth viability of HaCaT cells were investigated. The results show that the extraction rate of collagen by hot water method is higher than the other two methods, and all three collagens contain the collagen characteristic amino acids Gly, Pro and Hyp. The UV and IR spectrograms show that all three collagens have obvious absorption peaks near 222 nm, and there are absorption peaks of amide A and amide B and characteristic peaks of amide Ⅰ, Ⅱ and Ⅲ, suggesting that all three collagens belong to type I collagen with a three-stranded helical structure. And the results of scanning electron microscopy show that the three-stranded helical structure of collagen extracted by acid method is more complete and maintains the original structure of collagen fibers better than that of enzymatic method and hot water method. The collagen peptides extracts have the ability to significantly increase the viability of normal and UVB-damaged HaCaT cells in the range of 50?100 μg/mL, indicating that the enzymatic products of collagen of Sipunculus nudus have good potential applications in skin photoaging repair.