Ecol-physiological characters including population density and height, leaf length and width, culm lenth, internode length and chlorophyll content of Calamagrostis angustifolia were studied using field survey and controlled experiment for two water regimes. Different responses of C. angustifolia to water regimes were detected. The values of above indicators decreased as the water level increased under the variable water regime. However, for the different composition of communities resulted from different water conditions, these indicators reached the maximum on the zone occupied by C.angustifolia community. In contrast, under static water regime, these indicators showed a wave-like change, population density and height, leaf width, culm length and chlorophyll content in the treatment with static water level of 30 cm were significantly different from other treatments. Under variable water regime, C. angustifolia grew better and its growing stage came earlier than under static water regime. In wetlands, water conditions not only affected directly the growth of plants, but also indirectly influenced by the composition of communities and soil characters. Therefore, ecol-physiological characters of C.angustifolia were the results of both direct and indirect functions of different water conditions.