Leptin is a new obese gene (ob) product in animal , which related with feed intake , energy balance , lipid metabolism , reproduction and so on. The advances were summarized on structure , secretion and function of leptin. The effects and regulation of energy nutrient on the expression level of leptin were introduced , and the application prospects in aquatic animals were also discussed. Obesity is not the main problem of aquatic animal production, but the improvement of carcass quality and reproduction is the central goal of aquaculture. Some study indicated , leptin has had the remarkable regulative effect on lipid metabolism and neuroendocrine , the regulation of feed intake and energy balance could promote muscle produce , reproduction , milk secretion etc , at the same time the leptin expression of ob gene was affected and regulated by adipose tissue volume and cell size , energy intake , some hormones and so on. Therefore , ob gene and leptin not only have influence on gene effect of adipose deposit and improvement of carcass quality in aquaculture , but also show the potential that the Leptin expression could be regulated through nutritional ways. Energy intake 、energy utilization and lipid metabolism could be regulated by feed intake , energy assembling of diet , gain range and so on , consequently which regulated the expression of ob gene and the output ,the sensitivity ,the receptor activity of its product leptin , ultimately the objective of improvement of carcass quality , increase of reproduction , regulation of physiological metabolism and healthy protection could come true. To get this goal is possible and has important theory significance and practical value.