In recent years, the vegetation distribution decreased significantly in Lake Dongting due to global change and intensive human disturbance, and has induced significant concerning about the decrement of service functions. In order to reveal the vegetation dynamics and its dominant influencing factors of Triarrhena sacchariflora and Carex sp.community ecotone, we took Beizhouzi lake-shore as an example, and investigated the vegetation characteristics and soil environmental characteristics in the ecotone of T. sacchariflora and Carex sp.community in the Lake Dongting based on belt sampling method and indoor measurement. The results showed that: soil moisture decreased significantly along with increment of elevation. Total carbon, total nitrogen, total phosphorus and pH had significant difference between these belts, while conductivity and total potassium displayed similar patterns. Vegetation species richness and diversity index decreased firstly and then increased along with elevation. Biomass of T. sacchariflora increased significantly along with elevation, while biomass of Carex sp.community exhibited increase firstly, followed by decrease with elevation. Canonical correlation analysis showed that soil moisture was significantly correlated with both biomass accumulation of T. sacchariflora and Carex sp., and vegetation species richness and diversity, indicating that soil moisture is the key dominant factor influencing vegetation dynamics in this ecotone.