In this work, pepsin-solubilized collagen (PSC) was extracted from the body wall of sea cucumber, and its degradation and structural changes during heat treatment were studied. It was found that the denaturation temperature of PSC was 35.3 ℃. When PSC was heated at 40–70 ℃, the triple helix structure was coiled, and the α-helix structure was severely damaged; but after cooling, a strong gel system could still be formed by intermolecular hydrogen bonding and disulfide bonding interactions. When the heating temperature exceeded 70 ℃, the α-peptide chain of PSC began to be gradually degraded into small polypeptides, and the intermolecular cross-linking effect was too poor to form a gel system.