Abstract: In order to study the effects of drought stress on photosynthetic characteristics of two energy resource shrubs, one-year-old Elaeagnus angustifolia L. seedlings and Tamarix hohenackeri Bunge cutting seedlings were selected as the experimental materials. Their leaf chlorophyll content and photosynthetic parameters under four different soil water conditions were measured in the water-controlling pot experiments. The results showed that the leaf chlorophyll content of T. hohenackeri was lower than E. angustifolia at various soil moisture conditions, leaf chlorophyll content of T. hohenackeri increased under moderate drought stress and there was still a higher content of E. angustifolia in severe drought stress conditions. With the aggravation of drought stress, the net photosynthesis rate(Pn), transpiration rate(Tr)and stomatal conductance(Gs)of both two tree species showed a tendency of decrease, and under moderate drought stress, Pn and Tr decreased more significantly, while the intercellular CO₂ concentration(Ci)increased. The diurnal variation curves of both Pn and Tr of T. hohenackeri displayed the two-peak pattern with a typical midday depression at 11:00 under different levels of drought stress, while Gs presented a single-peak curve. The diurnal variation of Pn of E. angustifolia displayed a single-peak curve, which was significantly higher in the morning than in the afternoon. Tr and Gs of two shrubs were displayed in two-peak pattern and positively correlated.