Abstract:In order to understand the effect of drought stress on the growth of Phalaenopsis pulcherrima, the changes in contents of photosynthetic pigments, osmotic adjustment substances and non-structural carbohydrates in leaves were studied. The polyethylene glycol 6000 (PEG) solution was used to simulate drought stress. The results showed that plant water content and fresh weight decreased gradually with increment of PEG concentration, and plant water content and fresh weight decreased significantly treated with PEG from 13.75% to 14.84%. The contents of chlorophyll a and b decreased significantly in leaves treated with PEG. With the decreasing of plant water content, the contents of soluble protein and starch (St) decreased gradually, while the soluble sugar (SS), NSC (non-structural carbohydrate), and SS/St in leaves increased at first and then decreased. Therefore, the drought stress simulated by PEG could significantly affect plant water content and accumulation of photosynthetic products in leaves. Under light drought stress, soluble sugar played an important role in resistance to drought, while the physiological metabolism of P. pulcherrima would be seriously influenced under severe drought stress.