Abstract: In the context of evolving economic and industrial landscapes, the formation of small wetlands in proximity to rural settlements has emerged as a notable phenomenon. It has been observed that these wetlands established close ecological interactions with their surrounding environment, thereby contributing to the development of intricate and adaptable ecosystems. The small wetland-settlement system constitutes an open complex adaptive system (CAS) integrating social, economic, and ecological dimensions. This structural configuration is thus representative of the core tenets of complex adaptive systems theory, particularly in its ability to demonstrate multi-agent learning and non-linear interactions. The Northern Zhejiang Plain was selected as the research area for this study, and the historical evolution of small wetlands and rural settlements was systematically traced from the Neolithic period to the modern era. To this end, the present study employs the stimulus-response model and the echo model from complex adaptive system (CAS) theory to explore the causes of the formation of small wetland-settlement systems. Current research unequivocally establishes wetland ecosystems as a continuous driver of rural settlements evolution. The relationship under scrutiny here unfolds across distinct temporal phases, beginning with early hunter-gatherer societies that were dependent on wetland resources and concluding with the contemporary environmental movement. In between these phases lie the agrarian transformation to settled agriculture and the subsequent industrial expansion. Each era is characterized by a distinct reciprocal relationship between small wetland and rural settlements, illustrating how wetland health has historically influenced settlement patterns and how human activities have reciprocally impacted ecological conditions. The stimulus-response model reveals that rural communities absorb environmental stimuli and generate behavioral responses through internal adaptive learning, which evolves multidimensionally from basic adaptation to proactive transformation and ultimately to intelligent innovation. At its core, it is a dynamic process of adjustment. It adjusts to the three-dimensional stimuli of livelihood needs, production drivers, and ecological constraints. The echo model reveals that dynamic interactions between rural settlements and wetlands are mediated by unequal resource competition and sharing, exhibiting inherent disequilibrium. This theoretical framework elucidates the dynamics of asymmetric resource allocation processes, which are instrumental in facilitating system-level adaptation. The model demonstrates how competitive pressures and cooperative exchanges coexist in a state of non-equilibrium flux. The research further elucidates that when the enhancement capacity of the wetland subject surpasses the impairment capacity of the settlement subject, specifically when Wetland-Develop (WD) > Human-Impair (HI), where WD represents the enhancement capacity of wetland subjects and HI denotes the impairment capacity of settlement subjects—the small wetland-settlement system meets the prerequisites for sustainable development. This critical threshold—defined as the condition where wetland enhancement capacity (WD) exceeds human impairment capacity (HI)—defines the transition point at which ecological resilience becomes more significant than anthropogenic degradation, thereby providing a quantifiable benchmark for system viability assessment. The present study proposes a systematic conservation strategy, guided by the principles of complex adaptive system (CAS) theory. The strategy is composed of three key components: enhanced adaptive learning, optimized resource allocation, and innovative conservation approaches. The strategy has been developed with the objective of promoting the sustainable development of small wetlands and rural settlements. This can be adopted by other systems with similar characteristics and is crucial for preserving the local ecological balance.