Abstract：Abstract：We collected 6 crisp melon（Cucumis melo L. var. conomon Makino）varieties as experiment materials and studied the sucrose content of crisp melon fruit and sucrose metabolism enzymes．The results showed that there were big differences in sugar contents of different crisp melon varieties．The soluble solid contents and sugar contents of 3 va rieties‘Fengtaiyuegua’，‘Tianjiyuegua’，‘Liujiyuegua’were higher．The sucrose phosphate synthase activity became higher and higher as the fruit grew and matured，and the enzyme activity was the highest in‘Tianjiyuegua’．While the invertase activity became lower and lower along with the fruit development．The activities of acid invertase and neutral invertase were the lowest in‘Fengtaiyuegua’and‘Tianjiyuegua’during various development stages．The activities of neutral invertase were high in‘Maojiyuegua’，‘Panjiyuegua’，‘Qingpiyuegua’，‘Liujiyuegua’，and decreased with the fruit development．There were no obvious changes in other varieties sucrose metabolism enzymes activities in crisp melon fruit expect‘ Liujiyuegua’．These results indicated that the differences in sugar contents of different crisp melon varieties was determined by the activities of sucrose phosphate synthase，acid invertase and neutral invertase，and the acid invertase took the leading place．
