In this study, the sixyear Catalpa bungei clone (“91”) was fertilized via three fertilization schemes, i.e. the integration of water and fertilizer (WF), hole fertilization (HF) and no fertilization (CK) for analyzing the effect of fertilization on the growth of C. bungei. In addition, this paper also studied the effect of fertilization on the content and temporal dynamics of the nonstructural carbon (NSC) in tree organs, and explored the response mechanism of NSC allocation to fertilization, providing a theoretical basis for evaluating the carbon pool of C. bungei stand. The results showed that: (1) undergoing fouryear fertilization, the tree height and diameter at breast height (DBH) of HF increased 4.7% and 7.1%, and those of WF increased 7.1% and 20.5% compared with CK, respectively. (2) Different fertilization regimes did not significantly change the soluble sugar content in each organ, but the WF significantly increased the accumulation of starch and total NSC in roots. The soluble sugar and total NSC contents were more distributed in leaves and coarse roots, and starch content was higher in roots. (3) Different fertilization regimes did not significantly change the soluble sugar content during each growth period, but the WF significantly increased the starch and total NSC content during the initial and final period of growing season. The sugar and total NSC contents in leaves were consistently consumed throughout the growing season. One part of the sugar in branches was consumed to support leaf growth, and another part was stored in the form of starch. The NSCs from leaves and branches captured by roots were converted into starch, then stored to help the tree fight low temperatures. In conclusion, C. bungei followed the NSC allocation strategy of “carbon consumption (initial stage)carbon consumption (middle stage)carbon accumulation (final stage)”. In conclusion, the application of water and fertilizer integration technology could significantly improve the biomass and productivity of C. bungei, which was worthy of priority in forest fertilization in the future.