Abstract: The differences of physiological and biochemical characteristics between leaf chlorosis tobacco plants and normal tobacco plants were studied. The result showed that the ratio of dry to fresh weight of chlorosis tobacco leaves were lower than those of the normal ones, the contents of chloroplast pigment were obviously lower in chlorosis leaves than in normal tobacco leaves, the degradation of chlorophyll a was faster than that of chlorophyll b, and the degradation of chlorophyll was faster than that of carotenoid. The contents of malonaldehyde and soluble sugar were higher in chlorosis leaves than in normal tobacco leaves. The differences in soluble sugar were significant, but those of root vitality were not significant, compared with normal tobacco plants. Reducing sugar and nicotine contents were low in stalks of leaf chlorosis tobacco plants, but starch contents were high. The contents of total sugar and the reducing sugar of lower leaves were higher, but nicotine contents were lower in chlorosis tobacco plants than in normal tobacco plants. The differences in protein and total nitrogen contents in the leaves and stalks were not significant between chlorosis and normal tobacco plants.