Prescribed burning is of great importance in wetland management worldwide, and has many impacts on wetland plants including ecophysiological influences. However, the knowledge on the plant regrowth characteristics after fire is not well documented. A case study on the ecophysiological characteristics of the dominant plant species, Calamagrostis angustifolia after prescribed burnings was conducted in a Sanjiang Plain wetland, northeastern China. The stem density of Calamagrostis angustifolia increased significantly. Leaf chlorophyll, chlorophyll a and chlorophyll b contents were lower in burned plants than in control plants, consistent with previous observations with higher values of chlorophyll a/b in burned locations. These chlorophyll measurements indicated that a higher potential for photosynthetic activity after prescribed burning. Soluble sugar contents in the burned plants were higher than in unburned plants. Soluble protein contents in leaves of burned plants were lower than unburned plants at the beginning of the growing season, and then greater than unburned plants. Spring burning and frequent burning (annual burning) have larger effects than autumn burning and less frequent burning (biennial burning) on the ecosystem, respectively. Prescribed burning affects the ecophysiological characteristics of Calamagrostis angustifolia as a related to stem density and nutrient contents, and these changes could have cascading effects on ecosystem function such as nutrient cycling and nutritional value to grazing animals.