Abstract: Summarize the current research status of natural pruning, analyze the limitations of existing research, propose research methods for natural pruning process, and provide theoretical basis for forest nurturing and natural pruning law research. Research suggests that current studies mainly focus on the relationship between the stand structure (non spatial structure) of artificial forests and natural pruning, as well as the influencing factors of natural pruning. There is still a lack of research on the mechanism and timing of natural pruning, and further research is needed on the natural pruning process of natural forests and the impact of spatial structure on natural pruning; Lack of universal research methods and absence of indicators that characterize the natural pruning time pattern in research indicators, making it difficult to support the study of natural pruning process patterns. The two indicators of branch age and leaf moisture content can compensate for the shortcomings of traditional indicators and can be used for studying the growth patterns of branches, the formation and shedding time of dead branches. The study proposes a method for branch classification and crown stratification, which divides branches into three categories based on their moisture content and leaf volume: live branches, semi dead branches, and dead branches; There are three types of branches: full leaf branches, half leaf branches, and no leaf branches. Divide the vertical layer of the tree crown into three layers: full leaf branch layer, half leaf branch layer, and no leaf branch layer. Research has shown that analyzing the vertical structure of tree crowns, the distribution characteristics and composition ratios of different types of branches, the age and moisture content changes of different types of branches, and their relationship with natural pruning have positive significance in revealing the mechanism and timing of natural pruning.