The experiment used three-year-old Blueberry varieties as materials and samples were taken at different stages of fruit and leaves development to determine the dynamic changes of glucose, fructose, sucrose, sorbitol, and sucrose synthase and invertase activities. The results showed that sorbitol is the main product of photosynthesis in blueberry leaves; the enzymes in the decomposition direction were much larger than those in the synthesis direction,and the acid invertase activity was always higher; the sucrose content and acid invertase activity were significantly negatively correlated. The sugar accumulation in blueberry fruit is mainly glucose and fructose, and the glucose content is higher than fructose; and acid invertase and enzymes in the direction of sucrose synthesis are the key enzymes for sugar accumulation in blueberry fruit.