It has been considering a preparing technique in due to distinguish the mountain topography layers in regions of high geodynamic activity of the Earth’s crust on the base of analysis of the digital relief models and on the set (composition) of characteristic dendrofl ora species as exemplified to Western Prebaikal Region (model polygon in Preolkhon Region). It is used the original technique of constructing digital relief models, basing on the principles of the method of relief plastic. The digital relief model can accurately provide the spatial boundaries of topography layers. With the above technique, four topography layers of relief of Preolkhon Region (West Prebaikal Region) have been determined: the watershed, slope, valley and aquatic. The character of dendroflora allows supplying the genetic connection layers. It is propose to divide some heterogeneous on the stretching topography layers on the elongated segments. It was established that typical set (composition) of dendroflora species (trees, bush, and small bush) is characteristic for each specific topography layer and its segment in study area of Preolkhon Region. This composition has been used for additional indication of topography layers subsequently. The proposed technique is more precise in comparison with traditional techniques in due to distinguish the topography layers.