Abstract: In this study, collagen was extracted from Rhopilema esculenta using hydrochloric acid-pepsin methodology, and its detailed structure were characterized by SDS-Polyacrylamide gel electrophoresis (SDS-PAGE), UV-visible spectroscopy (UV), amino acid analysis, Fourier-transform infrared spectroscopy (FTIR), circular dichroism (CD), and scanning electron microscope (SEM). The SDS-PAGE pattern of Rhopilema esculenta collagen presented an α-chain at about 135 kDa with a β-chain and γ-chain above 245 kDa. In addition, the UV absorption peak of Rhopilema esculenta collagen was centered at 233 nm, revealing that the Rhopilema esculenta collagen herein adopted the feathers of type I collagen with a possible subunit composition of α₁(I)₃. The most abundant amino acid in Rhopilema esculenta collagen was glycine, accounting for 25.99% of the total amino acids. Besides, the collagen in this work contained 15.94% imino acid. Results of Fourier transform infrared spectroscopy and circular dichroism suggested that the Rhopilema esculenta collagen presented a compact triple helix structure that maintained primarily by hydrogen bonds. The images of Rhopilema esculenta collagen under SEM observation showed mainly irregular networks consist mainly of multilayered fibers.