Abstract: A pot experiment was conducted to study the variations of the photophysiological characteristics of native bluestem (Bothriochloa ischaemum) in loess hillygully region under different soil moisture condition (80% and 40% field capacity) and different atmospheric CO₂ concentration (375 μmol·m^-2·s^-1 and 750 μmol·m^-2·s^-1). The results showed that drought stress decreased the maximum photosynthetic rate (P_{n max}), apparent quantum efficiency (AQE), stomatal conductance (g_s), transpiration rate (T_r), maximum photochemical efficiency (F_v/F_m), potential photochemical efficiency (F_v/F_o), and photosynthetic pigments contents, and increased the malondialdehyde (MDA) and proline (Pro) contents. Under sufficient moisture condition, elevated CO₂ concentration didn’t change the P_{n max} and the MDA and Pro contents significantly; under drought stress, elevated CO₂ improved the maximal fluorescence (F_m), F_v/F_m, F_v/F_o, photosynthetic pigments contents, and AQE, and the P_{n max}  under elevated CO₂ was increased significantly by 23.3%, and the MDA and Pro contents were decreased significantly, as compared with those under ambient CO₂ concentration. All the results suggested that elevated CO₂ concentration had definite compensation effect on the photosynthetic reduction of B. ischaemum induced by drought stress, and alleviated the damage of drought stress on B. ischaemum.