Studying decomposition processes and nutrient dynamics of aquatic plants is of great importance for better understanding of material cycles in aquatic ecosystems. In this paper, six aquatic plants (i.e., Phragmites australis, Zizania latifolia, Nelumbo nucifera, Nymphoides peltatum, Potamogeton crispus and Myriophyllum verticillatum) were chosen as the experimental materials. Using the mesh bag method, the decomposition processes and nutrient dynamics of the 6 aquatic plants was investigated in a laboratory environment for 64 days. Substantial differences in decomposition rates were observed among the 6 plants. The floating-leaved plants presented the highest decomposition rate, followed by the submerged and emerged plants in turn. For each plant, decomposition rate and residue composition varied by biomass density but had a similar temporal pattern. During the decomposition processes, the dynamics of phosphorus, cellulose and lignin contents showed the same variation trend across different plants. Phosphorus contents were decreased substantially in the first 4 days, followed by a slight increase. The phosphorus contents of the emerged plants was significantly lower than that of the floating-leaved plants and submerged plants during decomposition. Cellulose contents were decreased in the first 4 days and stabilized afterwards. The cellulose contents of the emerged plants was significantly greater than that of the floating-leaved plants and submerged plants during decomposition. Lignin contents were increased in the first place and then stabilized. Variation tends of carbon, nitrogen and hemicellulose contents in different plants' residues were different. The carbon contents of emerged plants kept stable at first, decreased then and increased at last. While the carbon contents of the floating-leaved plants and submerged plants fluctuated at first, decreased then and increased at last. The carbon contents of the submerged plants were significantly lower than that of the emerged plants and floating-leaved plants during decomposition. The nitrogen contents of the emerged plants increased slowly, while the nitrogen contents of the floating-leaved plants and submerged plants increased first, then decreased and settled out at last. The nitrogen contents of emerged plants were significantly lower than that of the floating-leaved plants and submerged plants during decomposition. The hemicellulose contents of the 6 plants settled out in the end of the decomposition, but they performed differently in the early stage of decomposition. The hemicellulose content of Phragmites australis settled out at first and then decreased. The hemicellulose content of Zizania latifolia increased first and then decreased. The other four plants' hemicellulose contents decreased first and then increased, and decreased at last. The hemicellulose contents of emerged plants were significantly greater than that of the floating-leaved plants and submerged plants during decomposition. Correlation analysis of decomposition rates and nutriment contents showed that the decomposition rates tended to be facilitated with increasing initial nitrogen, phosphorus contents; while the rates were slowed with increasing initial cellulose, hemicellulose, lignin contents and C/N, C/P, lignin/N. The main factors affecting the decomposition rates presented a temporal variation. In the early stage of decomposition, decomposition rates tended to be facilitated with increasing hemicellulose contents, C/N, lignin/N; while in the late stage, the rates were slowed with increasing lignin and the other factors played minor roles.