Abstract: The pygmy slow loris (Nycticebus pygmaeus) is a little studied primate endemic to Vietnam, Laos, eastern Cambodia and southern Yunnan province of China. The pygmy slow loris has been categorized as band Ⅰ in the first key protected wild animals in China and is one of the “extremely small population” in Yunnan province. Since the early 21st century, population of pygmy slow loris declines sharply. Urgent actions are required to promote them. We collect the ecological data of the most intensive field studies of pygmy slow loris, involve morphology, distribution, population surveys, food habits, breeding, sleeping sites selection and range, physiological ecology. On this basis, we summarize the ecological characteristics of pygmy slow loris, clarify its scientific significance and briefly discuss the current pygmy slow loris research hotspots and prospects.