Abstract: To investigate the physiological adaptation mechanisms of the tropical reef-dwelling sea cucumber Holothuria leucospilota under starvation stress, this study systematically measured its dynamic changes in oxygen consumption rate, ammonia excretion rate, and body wall tissue nutritional composition at 0, 7, 14, and 21 days. The results showed that the respiratory metabolism of H. leucospilota exhibited a typical stepwise decline pattern. The oxygen consumption rate decreased rapidly by 15% within 0～7 days and sharply declined by 65% by day 21, reaching (7.00±1.11) μg·g⁻¹·h⁻¹. The ammonia excretion rate displayed a slow decrease during 0～7 days, a sharp decline during 7～14 days, and stabilization during 14～21 days. In terms of nutritional metabolism, short-term starvation (21 days) led to a significant reduction in tissue moisture and lipid content (P < 0.05), decreasing by 2% and 28% from initial levels, respectively, whereas organic matter, crude protein, and total carbohydrate content showed no significant differences during starvation. The levels of 16 amino acids (including 9 essential and 7 non-essential amino acids) peaked at 7 days of starvation and then gradually declined, though they remained significantly higher than initial levels after 21 days (P < 0.05). These findings provide a scientific basis for optimizing feeding strategies in sea cucumber aquaculture.