Understanding the coupling mechanisms within and among ecosystems and revealing the functional laws of composite ecosystems are of significance in promoting the integrated restoration and protection practice of the Mountains-Rivers-Forests-Farmlands-Lakes-Grasslands-Sandlands in China. Considering the lack of systematicness and continuity in current restoration and protection projects, we took the temperate forest ecosystem of Changbai Mountain, which is rich in ecological resources, as the study area, and carry out the coupling modelling of its key elements, "water, soil, air and life".this paper coupled the key elements of the temperate forest ecosystem in the Changbai Mountain.Through analyzing the operation mechanism of the model, we explored the interactions among important sub-modules and the coupling mechanism of key ecological elements within the sub-modules, and constructing the parameters of the model with the constituent tree species and environmental factors of the temperate deciduous broad-leaved forests in the Changbai Mountains, we obtained the dynamic succession process of the temperate forests in the Changbai Mountains by running the forest window model for 1000 times. The results showed that the key elements, such as the degree days, the days of drought (lower than the days of the soil wilting point), soil available nitrogen, and available light mutually influenced each other, which comprehensively determined the regeneration, growth, and death process of each tree. The simulation results also showed that during the succession dynamic process in the Changbai Mountain temperate forest ecosystem, there were distinctly compositional characteristics of tree species in four periods: from 0 to 70 years, from 70 to 170 years, from 170 to 280 years, and from 280 to 400 years. Compared with the actual succession process, we found that the simulated forest had obvious periods. Betula platyphylla and Populus davidiana were pioneer species in succession, accounting for a total biomass of 55% during the 0-70 year period. However, their biomass decreased and eventually disappeared after 70 years; Transition tree species such as Tilia amurensis, Quercus mongolica, and Fraxinus manshurica further altered the growth environment. Initially, Pinus koraiensis accounted for only about 3% of the biomass 170 years ago, but its biomass continued to increase as succession progresses. During the 170-280 year period, Pinus koraiensis biomass accounted for 15% of the total forest stand. After 280 years, Pinus koraiensis biomass represented 50% of the total. These results indicate that the simulated forest dynamics conform to the laws of succession, which fully demonstrating the rationality of the coupling mechanism of multiple key elements "water, soil, air and plant", which provides a scientific theoretical basis and methodological technology for promoting research on the coupling of multiple ecological elements at the scale of the ecosystem.