Abstract: Taking Alcimandra cathcartii, a Class II key protected plant in Laojunshan region of Wenshan National Nature Reserve, as the research object, in order to investigate the structure and development trend of the wild natural population of Alcimandra cathcartii which is a second-class protection plant protected in Laojunshan Area of Wenshan National Nature Reserve, the sample square survey was used, we obtained the statistical results. With the diameter class instead of age, this study applied a smooth technique to compile static life table, plotted the survival curves and four survival function curves, and used a time series model to predict. The results showed as follows. the age structure of the Alcimandra cathcartii population was inverted "J" type, seedlings and young trees has the largest number of individuals, the quantitative analysis of population dynamics was repeately fluctuating,its population stability was poor. The survival curve tends to be Deevey-Ⅱ type, the mortality rate of other age groups was not different. Survival analysis showed that the population had the characteristics of sharp decline in the early stage and Invariable in the middle and late stages. Time series prediction shows that the future population of Alcimandra cathcartii will increase in the future as a whole, but due to the high mortality rate of young, the population renewal is limited and the population may also decline. It is recommended to strengthen conservation management, habitat protection.