The damage of tobacco spot disease with different dangerous degree were studied on tobacco output value of different part leaves, which included the 4th-7th, 8th-10th, 11th-14th and 15th-19th leaves from the bottom up to the terminal of tobacco plants, during flue-cured tobacco modulated time. The result showed that there was no distinct divergence output loss between the 8th-10th and 15th-19th leaves infected by tobacco spot disease with any dangerous degree, but the output of 4th-7th and 11th-14th leaves were affected when the damage from tobacco spot disease extended to 3~4 grade. The output loss was remarkable negative correlated to disease grade of the 4th-7th leaves, and was extreme remarkable strong negative correlated to that of the 11th-14th or 15th-19th leaves. With the 0.5 grade damage degree, the output value of all part leaves begin to decline and its loss get more and more increscent with the aggravating damage. There was extremely remarkable negative correlation between the output value loss and the disease grade of 15th-19th leaves, however, the output value loss was extreme remarkable strong negative correlated to that of the 4th-7th, 8th-10th and 11th-14th leaves. The disease grade of different tobacco leaves was remarkable strong negative correlated to the proportion of middle grades tobacco leaves and was extremely remarkable strong positive correlated to that of low grades tobacco leaves.