Abstract: Reed marsh in the western Songnen Plain is a unique ecosystem affected by many environmental pressures, including low precipitation and soil salinity with associated high pH, both of which contribute to heavy degradation of the marsh. Water plays the key role in wetland structure and function, and determines the biogeochemical cycling, and dynamics of vegetation and other biotic populations. In order to understand how to conserve and effectively use available water resources, cycles of dry-wet alternation (soil dried to 35% field water capacity and 10 cm flooding, respectively), and treatments with varying numbers of cycles per season were applied during reed development in this study. The growth and photosynthetic physiology responses, and the absorption and accumulation of ions in the above and underground organs were determined. Compared to long dry and wet conditions, cycles treatments of 1,2, and 4 dry-wet alternations improved reed growth and physiological indicators. For instance, biomass accumulation and photosynthesis were enhanced, and saline ion accumulation was reduced. With increased alternation frequency, and correspondingly shorter duration of drought or flooding stress, the negative effects of extreme wet or dry conditions on reed were alleviated, and its growth and development were promoted. Flood irrigation in the earlier stages of reed growth (June, July and August) improved growth ability, accelerated biomass accumulation, enhanced photosynthesis, and reduced Na⁺ absorption and accumulation. Two (C₂) and 4 dry-wet (D₂) alternating cycles, during which less water were used, facilitated high reed production and good quality in saline-alkaline wetlands. Flooding later in the growing season resulted in greater accumulation of Na⁺ in the above-ground organs. This indicates, a possible method for removing Na⁺ from the soil through the harvest of above-ground biomass after flood water irrigation to degraded reed marshes in August and September.