This experiment was carried out to study the influence on the abscission of tobacco green leaves, yields and quality by the application of lime and boras. The results obtained are as follows; 1. The breakdown of tobacco green leaves occurred from 40 to 80 days after transplanting. According to the progress of growing stage, the breakdown leaves advanced to upper leaves in stalk position. 2. The number of breakdown leaves were increased by application of lime and application of borax have a remarkable effect for the control of breakdown leaves. 3. Application of lime were decreased to total-sugar, lignin and borone but borax were increased to borone and lignin content in leaf tobacco at 50 days after transplanting time. 4. It was found that perfective prevention of breakdown leaves could not deped on annual application of borax. 5. The optimum amount of lime and borax were found that lime was 120kg/10a and borax was 1.2kg/10a for the prevention of breakdown leaves, yields and quality.