Abstract: Drought is one of the stress conditions that often severely effects plant growth. The loss of agricultural production due to drought stress is estimated to nearly equal the total losses caused by all other environmental stresses. In this study, the photosythetic parameter of Chenopodium album L. under artificially simulated drought stresses were examined to provide a theoretical basis for effectively increasing agricultural production in arid areas. C. album L. was grown from freshly harvested seeds under natural light. Six pots of plants showing similar growth was treated with drought stress by controlled irrigation: 15% water content of soil was kept by weighing, watered once two days for the entire experimental process; the pots were protected from exposure to rain. The photosythetic parameter of Chenopodium album L. was determined with LI-6400 Portable Photosynthesis System in the first ten-day of July. The result shows that the diurnal variation curve of photosynthesis in the leaves of C. album L. assumes was a two-peak pattern, had the middle-day depression and belongs to the stomatal limitation type under the drought stress condition. Its net photosynthetic rate(Pn) reached the peak value at about 8:00. Compared with the plant growing under normal condition, the photosynthetic light saturation point (LSP), the net photosynthetic rate(Pn), apparent quantum yield(AQY), carbondioxide saturation point(CSP) and carboxylation efficiency(CE) all reduced, was 1 200 μmol photon·m^-2·s^-1, 8.01 μmol photon·m^-2·s^-1, 0.016 1 μmol CO₂·mol^-1 photons、1 200 μmol CO₂·mol^-1 and 0.017 6 μmol·m^-2·s^-1 respectively; However, light compensation point (LCP),carbondioxide compensation Point(CCP) all increased,was 44.88 μmol photon·m^-2·s^-1 and 46 μmol CO₂·mol^-1 respectively. Under the drought stress condition，although the photosynthetic capability of C.album L. decreases, but comparing C.album L. with other C₃-plant it still have a great capability of assimilation CO₂. Chenopodium album L. is a drought-resistance plant.

Key words: Chenopodium album L., drought-stress, photosynthetic characteristics, capacity of assimilation CO₂, drought resistance