Abstract: Abstract：Studies on the influence of different transplanting periods on the activity of sucrose metabolizing enzymes and Chemical composition of leaves by filed test. The results indicated that transplanting of tobacco in November 18,the nitrogen metabolism mainly to the accumulation of carbon-based change is more balanced in the growth and development in the period , However, on the basis of the transplant period, It should appropriate additional nitrogen in the growth process of tobacco in order to enhance nicotine content of the the upper leaf.So that chemical composition tends to coordinate of the upper leaf.The transplanting periods is too earily or too late, As the climate factors will lead to carbon and nitrogen metabolism imbalance in the development of the whole tobacco, The Chemical composition of tobacco is lack of coordination.