Analysis of numeric dynamics of populations has been widely used to study endangered species, however, its application to China orchid is rare. By investigating biological characteristics and reproductive behavior of Cypripedium lentiginosum, an orchid endemic to Yunnan of China, the number surviving in each age-class, the frequency and number of filial generations, and the reproductive behavior and mechanisms are explored. Internal distribution pattern is figured out based on genet frequency; on the basis of the number surviving in each age-class and the number of filial generations, the population static life table and fecundity table are made, the survival curve and age pyramid are drawn, and Leslie matrix model and the density-dependent growth model Nt=658e0.211t are structured to predict numeric dynamics; reproductive behavior and breeding strategy were analysed by observing phenological characteristics and pollination biology. Based on these, we analysed the relationship between the numerical dynamics and reproductive behavior, as well as its internal distribution pattern and age pyramid. We found that C. lentiginosum showed a clumped dispersion distribution pattern, its age pyramid is pyramid-bell shaped, and the population survival exhibited a Deevey I shape; the net reproductive rate and the intrinsic and finite rates of increase for C. lentiginosum were comparatively high, indicating the population is expanding; the population growth is affected by self-density, and the prediction model based on this factor is Nt=6000/(1+e2.094-0.211t), which is suitable for predicting numeric dynamics of C. lentiginosum. The species are endowed with both asexual and sexual reproduction. The former does not increase individual quantity, but sustain the current genetics of the population and accumulate energy for sexual reproduction, while the latter involves pollinating flowers by mimicking brood-site to lure hovefly into the labellum, whose fruit set rate is 54.37%±6.08%, the fruits grow into sufficient young plants and most of them could live through the sexual reproduction stage. Sexual reproduction generates progeny many times over a long period suggesting this kind of reproductive mode is the main factor affecting numeric dynamics of a population. The species′ successful reproductive strategies and their impacts on numeric dynamics in spatial and age distribution indicate that the population development of C. lentiginosum corresponds to its biological characteristics. Discontinuity and narrowness of growing space in the habitat are the main factors restricting population development, however, at present, the species does not need, nor will it prosper from, ex-situ conservation.