To explore the C, N, and P ecological stoichiometric characteristics of leaves and fine roots of Taxodium distichum (L.) Rich in the water-level fluctuation zone of the Three Gorges Reservoir (TGR) region. The C, N, and P content and their ratio in leaves and fine roots of T. distichum in Zhong County under three submergence treatments—Deep Submergence (DS), Moderate Submergence (MS), and Shallow Submergence (SS) were measured and analyzed in July 2018. The results showed that: (1) The C content in leaves of T. distichum showed a trend of SS>DS>MS group, and SS group was significantly higher than that in MS group; there was no difference in C content of fine roots under three submergence treatments. (2) The N and P content in fine roots showed a synergistic growth trend of DS < MS < SS group; the N and P content in leaves showed a cooperative decrease trend of DS>MS>SS group, and the N and P contents of the leaves was about 3 times and 2 times of that in fine roots, respectively. (3) The C/N and C/P ratios of the leaves were significant or extremely significantly lower than those of fine roots in submergence treatment group; the N/P ratio was higher than that of fine roots, and its ratio was relatively constant. Moreover, the N/P ratio between leaves and fine roots showed a trend of SS > DS > MS group. (4) Correlation analysis showed that there was a significant negative correlation between leaf P content and fine root N content, and the leaf N/P ratio was significantly positively correlated with fine root N/P ratio. This work demonstrates that the leaves and fine roots of T. distichum have integrity in the process of growth and metabolism, the nutrients and photosynthetic products are distributed between the above- and below ground parts to maintain the dynamic balance of nutrients, so that the T. distichum has homeostasis and thus adapt well to and respond to changes in the water-level fluctuation zone of the TGR region.