Abstract: Abstract: Sea cucumbers show high nutritional and medicinal value. Fresh sea cucumber can be degraded after being harvested out of water because of the autolytic enzyme and microorganism in sea cucumber. It can also be degraded even if the enzyme and microorganisms in sea cucumbers lost their activities, which is known as non-enzymatic degradation. Non-enzymatic degradation of the body wall gel is an important factor restricting the development of sea cucumber products. The high hydrostatic pressure (HP) technology is a novel method which shows various advantages. In order to investigate the mechanism of stability and degradation of sea cucumber body wall under high hydrostatic pressure (HPSC), the sea cucumbers were treated with high hydrostatic pressure (650 MPa) for 40 min. The changes of textural parameters, histological features of collagen fibers, moisture status, moisture distribution, and biochemical parameters were explored by accelerated destruction test, which was performed at 37℃ and the samples were stored for 30 days at this condition. The results showed that the hardness, chewiness, restorability and other texture profile analysis (TPA) parameters had a significant downward trend during storage (P<0.05). The hardness of HPSC decreased sharply from 840.50 to 23.33 after storage for 30 days. Besides this, the elastic modulus, viscous modulus and other rheological parameters of HPSC also decreased significantly (P<0.05). The elastic modulus E1 decreased from 2.24×104 N/m2 to 0.40×104 N/m2. But the descending rate of these parameters was much lower than that of the sea cucumber treated by high pressure and high temperature, which indicates that high hydrostatic pressure can put off the degradation. The collagen fiber of HPSC had a three-dimensional network structure according to the Van Gieson stain image, similar to that of fresh sea cucumber. This indicated that the thermal gel structure did not form in collagen fiber under high hydrostatic pressure treatment. In addition, the collagen fiber was degraded significantly after stored for 20 days. Longitudinal relaxation time and transverse relaxation time-weighted imaging showed that both the combined water with a short relaxation time and the free water with a long relaxation time distributed evenly during the early storage time. After 20-day storage, the combined water transformed into the free water, which resulted in the significant increase of water activity (P<0.05), and this was due to the structure destruction of sea cucumber body wall. The level of ammonium nitrogen, free hydroxyproline, and ε-amino in the HPSC had a significant increase during the storage (P<0.05), indicating that the collagen of sea cucumber body wall had been degraded. Therefore, the gel deterioration of sea cucumber body wall was largely due to the breakage of collagen fiber, the conversion between the bound water and free water, and protein degradation. Previous studies have demonstrated that sea cucumbers treated by high temperature and high pressure had the self-degradation phenomenon during storage, and temperature is an important factor leading to the degradation of sea cucumber body wall. But the results of this research showed that the temperature was not the only factor causing the degradation of sea cucumber body wall, and sea cucumbers treated by non-thermal high pressure can also be degraded during the storage time. For this reason, other efficient measures that can inhibit the self-degradation should be taken in order to extend the shelf life of sea cucumber.