Abstract: In order to reveal the mechanism how nutrients promote tuber development, the changes of endogenous hormones，yield and quality in the process of tuber development in potato(Solanum tuberosum L.) were analyzed under different nutritional levels. The results showed that in tuber development, under- or over-supply of nutrients reduced ZT content at initial stage and IAA, ABA and JA content at middle stage, but increased GA content in the whole process, which caused GA/ABA and GA/JA to be off balance in the key stage of tuberization. Appropriate nutrient supply could keep higher ZT content at initial stage and higher ABA, JA and IAA content and lower GA content at middle period, which could satisfy the demand of important hormones in every stage of tuberization and keep GA/ABA and GA/JA at reasonable levels during tuber formation. The results also showed that under- or over-supply of nutrients promoted the formation of soluble sugar, reduced the formation of starch at late stage of tuber development and shortened the fast growth period in process of tuber formation.