Abstract: Abstract: The changes on the key enzymes activity in carbon and nitrogen metabolism and metabolites during the development of oriental tobacco leaves with different genotypes in Zhejiang Xinchang were studied. The results show that during the development of the oriental tobacco leaves, the activity of acid invertase(INV) was decreased; the changes of GS reached its peak in the 20dans in Samsun, but in the 30dans in Basma and Canik ;the activity of PAL was decreased in the 30dans; The content of total nitrogen was decreased with the mature leaves, but nicotine、total carbon and soluble total sugar were increased. Different varieties, carbon and nitrogen metabolism key enzyme activity and the content of metabolites were different.