Abstract: From 1982 to 1987 we investigated the mineral nutrient and the rule of requirement for lonyan tree. The mineral nutrientlevel of longan trees is relative with "on" or "off" year of longan tree. The annual variation of mineral nutrients shows a pattern of "v". Longan tree is more sensitive to potassium content tnan nitrogen and phosphorous content. We consider that potassium fertilizer application is the most important for longan tree.