Based on the data collected from the plots investigation along with the implementation Levins, Shannon weiner and niche overlap formulas, this paper investigated the niche breadth values and niche overlap values of the main tree species were measured in the natural forestry of Magnolia sieboldii and the age structure of Magnolia sieboldii The results showed that: The descending order of niche breadth value was to some extent in accordance with that of important values, but Enkianthus chinensis is different from others for its strong adaptability. The values of niche overlap were relevant to niche breadth in that the populations with wide niche breadths usually had high overlap values with the other populations. The niche overlap values among the populations with the same or similar environment requirements and similar biological properties were also higher. For example, Magnolia sieboldii and Enkianthus chinensis, with the same shade-tolerant characteristic, had high overlap value. Through this niche research it was shown that Magnolia sieboldii,is characterized by scattered distribution，poor regeneration and less competitive advantages with associated species in the community. Thus, Magnolia sieboldii was easily influenced by community variation.It was found that populations with the same ecological characteristics could form a fine relation in the same habitat when resources were sufficient. This finding provided further support for linsizu’s theory that the relationship between niche overlap and competition was not positively correlated. It was also found that the age structure of Magnolia sieboldii was not integrated as young trees were absent, Such inconsistencies threaten population development. Water condition, for example, was an ecological factor which affected the presence of Magnolia sieboldii,and its high altitude distribution showed its need for low temperature. Magnolia Sieboldii grew well in Sanhuawu, while, its age structure in Qinliangtai was older than those in other plots, Qinliangtai and Sanhuawu can be regarded as key conservation habitats and it can be noted that the dynamic differences brought about by the variance between the two habitats above would merit further exploration.