Abstract: In order to study the relationship between light and quality of tobacco leaf， the potculture experiments were conducted in intermediate altitude area of Sichuan province. Shadingcontrolled experiment were conducted to achieve five different irradiances of 100%（T1），60%（T2），40%（T3），20%（T4）and 10% （T5）of full sunlight， the differences of leaf structure and the physics and chemistry characteristic and aromatic components of fluecured tobacco under different light conditions were studied. The results indicated that tobacco leaves thickness， rate of palisade tissue and spongy tissue thickness of leaves palisade tissue and spongy tissue reduced when light intensity decreased. The per leaf weight，thickness，weight per unit leaf area，leaf density and sugar content of flue cured tobacco were decreased under low light intensity. However，the content of stem ratio，nicotine，total nitrogen，potassium，chlorine，lutein，carotenoid and neutral aroma constituent increased. The research results provided a theoretical basis for tobacco planting in high and intermediate altitude area and the mechanism of formation of tobacco characteristics.

Key words: Tobacco, Light, Tobacco physical property, Chemical compounds, Aroma constituent