The problem of rational use of natural resources of the Cisbaikalia is related to the study of vegetation, assessment of its actual state, extent of disturbance, as well as the prediction of dynamic trends. The investigated territory of the North-Western Cisbaikalia lies within the area of contacts of several physiographic and biogeographical boundaries. Great species and coenotic diversity of vegetation associated with it. The present-day vegetation of the region was formed in the late Pliocene – early Quaternary periods. When studying the evolutionary transformation of plant communities palynological, palaeobotanical and radiocarbon methods are used. The diversity of plant communities and their dynamics were reflected on the middle-scale (1 : 500 000) vegetation map. In constructing the mapping model and the legend to the map the vegetation was classified on geographic, genetic and structural-dynamic principles developed by V.B. Sochava and his followers. The results revealed the main regularities of distribution and development of the vegetation of the North-Western Cisbaikalia, identified their disturbance and general development trends.