Abstract: Thuja koraiensis, a second-class nationally protected plant species, is a unique endangered tree species in Changbai Mountain, with important economic and ornamental value. In this study, the age structure, static life table, and survival function of T. koraiensis were established by using individual root diameter and age data based on investigation of wild resources in the main distribution areas of T. koraiensis. The population development trend was predicted by dynamic index and time series analysis. The results showed that the age-class structure of T. koraiensis population was in the shape of “∩”, which was a decline type. The survival curve of T. koraiensis population under the dark coniferous forest was the Deevey-Ⅲ type, and was Deevey-Ⅱ type in pure forest community. Population survival analysis showed that the survival function of T. koraiensis appeared irregular fluctuation under the dark coniferous forest. The population distribution showed dynamic features of sharp drop in early age period, stable in middle age period, and decline in old age pe-riod. In the pure forest community, the dynamic pattern was characterized by the stability in early age period, growth in middle age period, and recession in old age period. Dynamic index and time series analysis showed that the decline rate of dark coniferous forest community was slightly higher than that of pure forest community. Our results showed that T. koraiensis had some recovery ability and that artificial tending should be used to promote its normal regeneration.