The content of soluble solids， total sugar，sucrose, glucose, fructose and sorbitol and the activities of sucrose-metabolizing enzymes including acid invertae(AI), neutral invertse(NI), sucrose synthase(SS), sucrose phosphate synthase(SPS) and sorbitol oxidase(SOX) were investigated during the fruit development of cultivars ‘Kairyo Hakuho’, and the correlations between sugar accumulation and the activities of enzymes were further analyzed. Results showed that the content of glucose and fructose was the highest at the 30th after full blossom, while the sucrose was the main accumulation form of sugar and its content reached the highest at the 110th after full blossom. SS activity in the direction of synthesizing increased with fruit development and reached the highest at maturity with a rate of 19.0 μmol/(h?g). SS activity in the direction of breaking down was the highest at the early fruit development, then declined rapidly and enhanced a little at the late fruit development. The activity of AI and NI at the early fruit development was the highest, and then it declined and maintained at a low level. Sucrose was significantly positive correlation with SS?SD, and negative correlation with AI and NI, but there was no correlation between sucrose and SPS. Glucose and fructose was significantly positive correlation with AI, NI and SOX. Therefore, SS?SD was a key enzyme in sucrose accumulation, but SPS was not. AI and NI played an important role in glucose and fructose accumulation.