With the blueberry cultivar’Northland’as the test material,samples were taken at six stages,namely,dormancy stage,germination stage,young fruit stage,fruit expansion stage,fruit maturity stage and deciduous stage,respectively.Taking leaves,fruits,new shoots,annual branches and biennial branches,total nitrogen content,soluble protein content,glutamic-pyruvic transaminase and glutamine synthetase were determined.The results show that in the annual cycle,the total nitrogen content of’Northland’blueberry was 1.05%-2.98%,soluble protein content was0.62-2.82 mg/g,the content of glutamic-pyruvic transaminase was 3.87-15.36μmol/（g·h）·FW,and the content of glutamine synthetase was 0.32-2.99μmol/（g·h）·FW.The total nitrogen content of leaves and shoots,the soluble protein content,the activities of glutamic-pyruvic transaminase and glutamine synthase in the annual cycle of"Northland"blueberry showed an overall trend of first increasing and then decreasing.The total nitrogen content,the soluble protein content,the activity of glutamic-pyruvic transaminase and glutamine synthetase in the branches decreased first and then increased,the total nitrogen content and the soluble protein content in fruits showed a trend of gradual increase,the activity of glutamic-pyruvic transaminase showed a trend of first decrease and then increase,and the activity of glutamine synthase showed a trend of first decrease,then increase and then decrease.During the annual cycle,nitrogen changes to the leaf＞fruit＞new shoots＞phloem＞xylem.