Abstract:Cypripedium macranthos (Orchidaceae), the second-class protected plant in the National List of Key Protected Wild Plants, unlike most species in the genus Cypripedium, is mainly distributed in North China, Northeast China and Taiwan. In recent years, over-collection has led to a dramatic decline in both population size and the number of individuals. In view of the special distribution pattern and endangered situation of C. macranthos, we selected eight climate scenarios:historical, current, future (LIG, LGM, MH, Current, RCP2.6-2050, RCP2.6-2070, RCP8.5-2050, RCP8.5-2070), and then analyzed 38 environmental variables and 80 distribution points from the database and the latest field survey using maximum entropy (MaxEnt) model. The results showed that under the current scenarios, the suitable areas of C. macranthos were mainly distributed in Northeast China and North China, and five key environmental factors affecting its distribution were:mean UV-B of the highest month (UV-B3, contribution rate:54.0%), forest land (FOR, contribution rate:14.3%), precipitation seasonality (coefficient of variation) (BIO15, contribution rate:7.4%), temperature seasonality (standard deviation *100) (BIO4, contribution rate:6.8%), and Grass/Scrub/Woodland (GRS, contribution rate:4.6%). For the first time, UV radiation variables were applied to predict the geographic distribution of suitable habitat for Cypripedium, which were identified to have a critical influence on the distribution of C. macranthos. In the historical three scenarios, the total suitable area of C. macranthos firstly decreased and then increased due to the glacial period. Meanwhile, compared with the suitable area in the current scenario, those in the future four climate scenarios had an upward trend. Except for the Last Glacial Maximum, the distribution centroid of the suitable area for C. macranthos was located in Hebei Province, while those of the other seven climate scenarios were located in the southeast of the Inner Mongolia Autonomous Region, close to Liaoning Province. In the context of climate change, the adoption of conservation strategies such as comprehensive surveys in suitable habitats, regular monitoring of habitat and plant growth, and science education was essentially important for C. macranthos. This study can provide theoretical references for the development of conservation strategies of C. macranthos and even the genus Cypripedium.