Abstract: To investigate the differences in drought resistance among different flue-cured tobacco cultivars (lines) and to further delineate the mechanism of tobacco seedlings'physiological response to drought stress, the impacts of drought stress on the seedling growth, reactive oxygen metabolism, antioxidant enzyme activity, and photosynthetic fluorescence parameters of four main flue-cured tobacco cultivars (lines), Yuyan6 (Y6), Yuyan10 (Y10), Yunyan87 (Yun87) and LY1306, in Luoyang tobacco-growing areas were studied under laboratory conditions. Polyethylene glycol (PEG-6000) was used to simulate light (10% PEG-6000), moderate (15% PEG-6000) and severe (20% PEG-6000) drought stress, and the drought resistances of the four cultivars were evaluated with subordination function method and principal component analysis. The results showed that the physiological responses of different flue-cured tobacco cultivars (lines) to drought stress were significantly different. With the intensification of drought stress, Y6 presented the smallest decrease in relative chlorophyll content (SPAD value), superoxide dismutase (SOD) activity, catalase (CAT) activity and transpiration rate (T_r). LY1306 had the smallest drop in biomass, peroxidase (POD) activity, net photosynthetic rate (P_n) and maximal PSⅡ quantum yield (F_v/F_m). Yun87 showed the smallest decrease in PSⅡ actual photochemical efficiency (Φ_{PS Ⅱ}) and photochemical quenching coefficient (qP). Y10 had the largest decrease in biomass, SPAD value, SOD activity, POD activity, CAT activity, P_n, T_r and F_v/F_m. The comprehensive assessment results from the subordination function method and principal component analysis indicated that the drought resistances of Y6 and LY1306 were stronger, while those of Yun87 and Y10 were weaker.