A field experiment was conducted to find out the effects of nitrogen and potassium rates on the chemical constituents and physical properties of burley tobacco (1988； Burley 21. 1989； Burley 21 and KB 101) during successive two years. KB 101 was low in total nitrogen and total alkaloid contents and potassium/total nitrogen ratio of cured leaf. but high in the lightness, red and yellow color and filling power, comparing to Burley 21. The increasing rates of total nitrogen and total alkaloid contents were larger when nitrogen applied to 22.75kg/10a, but they were smaller when nitrogen applied above 22.75 kg/l0a. The potassium content, potassium/total nitrogen ratio, filling power and shatter resistance index of cured leaf were decreased by nitrogen fertilizer addition. The potassium content and shatter resistance index were increased by potassium fertilizer addition. The effect of nitrogen rate on the potassium/total nitrogen ratio of cured leaf was larger than the effect of potassium rate. When the nitrogen fertilizer being applied above 22.75 kg/l0a, there were no advantageous effects on the chemical and physical properties. It is considered to be sufficient that the potassium application is about 35.0 kg/l0a.