The continuous and intense human activities have greatly changed the structure, path and driving force of the natural water cycle evolution, which conversely influences the water security of human being. With the process of globalization and market economy, human activities not only affect the artificial development of water and soil resources, but also extend to the economic field. The "flow" of water trade contained in product has become an important internal factor that drives the evolution of the regional water cycle and affects regional water security. Traditional water cycle research, which focused on the watershed scale, is difficult to reveal the linkage, two-way feedback mechanism and co-evolution dynamic mechanism in water cycle among different regions. Starting from the phenomenon of continuous and water-intensive agricultural products export in Northwest China, this research elaborates the phenomenon, the process, the structure and their driving forces of the unitary natural water circular, nature-human society binary circular, and trading water circular within multi-regional social economic complex systems by theoretical analysis. We explicated the theoretical framework for constructing the "natural-social-trading" ternary water cycle in the inland river basin, including mode of process, driving force of water cycle, conceptual model, influencing factors and ecological environment effects. Furthermore, we discussed the frontier of water cycle research in inland river basin based on ternary water cycle model-social hydrology. We advocated that the future study on water cycle and water resources should focus more on the external forces driving the water cycle of the inland river basin and its two-way mutual feedback and co-evolution, providing theoretical references for the decision-making of water security, ecological environment security and ecological civilization construction in inland river basins.