Abstract: Secondary succession is a crucial ecological process for tropical forest restoration, and the interaction between soil nutrients and plant communities is a key factor driving this process. Therefore, elucidating the relationship between soil nutrients and plant community characteristics during tropical secondary succession contributes to a deeper understanding of the recovery mechanisms of tropical forest ecosystems. This study targeted early, mid, and late successional secondary forests in Xishuangbanna, employing the space-for-time substitution approach to examine the changes and interrelationships of soil nutrients and plant community characteristics. The results indicated that as tropical forest succession progresses, total soil carbon, total nitrogen, total phosphorus, nitrate nitrogen, and available phosphorus significantly increase, while ammonium nitrogen significantly decreases. Regarding plant community characteristics, the species diversity of the herbaceous and tree layers was lowest in the middle successional stage, whereas shrub layer diversity was lowest in the early stage. Tree layer biomass increased significantly during succession, rising from 9.7467 kg·m⁻² in the early stage to 119.1185 kg·m⁻² in the late stage. Root biomass of the plant community peaked during the middle successional stage. Correlation analysis showed that tree layer biomass was the most influential factor driving changes in soil nutrients during succession (individual effect = 0.174). Total soil carbon (path coefficient = 0.24), total nitrogen (path coefficient = 0.36), and total phosphorus (path coefficient = 0.20) were primarily directly influenced by tree layer biomass, while nitrate nitrogen (path coefficient = 0.30) and ammonium nitrogen (path coefficient = -0.30) were mainly directly influenced by tree layer diversity. Additionally, tree layer biomass and diversity indirectly promoted total nitrogen accumulation by increasing soil pH. Besides having a direct positive effect on total soil carbon, root biomass also indirectly positively influenced total carbon, total nitrogen, and nitrate nitrogen by altering soil bulk density. In conclusion, changes in plant communities during secondary succession, particularly in tree layer biomass and diversity, effectively enhance soil nutrient levels and promote the restoration of soil functions. This study provides a theoretical reference for understanding the mechanisms of tropical forest succession and restoration.