Abstract: In adult Juglans sigillata (30 year old seedling trees) and young Juglans sigillata (2 year old seedlings),leaves were tested by Kjeldahl method,Mo-Sb colorimetry,atomic absorption and curcumin colorimetry,N,P,K,Ca,Mg,Fe,Mn,Cu,Zn and B were detected to analyze the dynamic changes of the main nutrients of the leaves by different ages.which provided a recommendable sampling period for the nutritional diagnosis of the trees and a scientific basis for rational application of fertilizer.The results showed that:Annual changing patterns of Juglans sigillata leaf mineral elements at different ages were basically the same,the content of macroelements showed little fluctuation,and ranked as Ca>N>K>P>Mg,the content of N,P,K showed a downward trend,while the content of Mg showed an upward trend;The content of Ca increasedat first and then decreased;The content of micro-elements fluctuated largely,in the growth periodof young Juglans sigillata,the content of the elements ranked as Fe>B>Mn>Zn>Cu,andin adult Juglans sigillata,it was Fe>Mn>B>Zn>Cu.The content of B and Mn showed an increasing trend,Cu and Zn showed a downward trend,the content of Fe fluctuated,and showed an up-down-up-down trend.Correlation analysis showed antagonism or promotion among the elements,the content of N,P,K showed significantly positive correlation,while N and Cu,Ca and Fe showed significantly positive correlation.On the other hand Cu and Ca,Mg content showed significantly negative correlation.The absorption of mineral nutrients by the leaves in different phenological periods was different,in pollination flowering period,N,P,K,Zn and Cu were demanded at most,the requirement of N,P,K was large in fruit enlargement period and hardcore period.The research shows that the nutrient elements of adult Juglans sigillata leaves were relatively stable from June 29th to August 10th.While for young Juglans sigillata,the relatively stable period was from June 21th to August 4th,which is recommended as suitable sampling periodfor the nutrition diagnosis of theleaves.It is also recommends that toapplythe key fertilizers twice a year,first time in late May and early June during the fruit enlargement period,and second time in late September after the harvest,applying the organic fertilizers deeply as a base fertilizer for the next year.