For the electronic Atlas of North Asian regions development, a geoinformation system (GIS) “Natural Environment of the Lake Baikal Basin” was developed by modifying the fund map information on the basis of the constructive geosystem approach. The purpose of its creation was information support of regional programs of geoecological analysis as a method for assessing the ecological state of the natural environment. A set of methods for modifying and structuring geographic information into a single thematic GIS is presented on the basis of abstract concept about the properties of geosystems and taking into account the capabilities of modern GIS technologies. The specificity of the study lies in the further developing polysystemic mapping as a variant of integrating geographic information. The unified information structure of the thematic spatial data developed on its principles makes it possible to identify the most diverse aspects of geosystems under a united territorial grouping of information. On the basis of constructive methodology, a new capacious content of the research object is formulated, which differs from that in private geographic disciplines. The geosystems are considered both as ecological (natural) environment, and as an inhabitancy of human (as a biological species), and as a resource base of its economic activity. Such an approach ensures the transfer of geosystem geographic information into indicative ecogeographical dependencies. The properties of geosystems indicating environmental conditions and the state of the natural environment have been studied using a set of cartographic approach methods: geosystem analysis, ecological indication, as well as methods for identifying, interpreting and systematizing geographic information into a single GIS. The initial thematic base of the research is made up of fundamental cartographic works of the V.B. Sochava Institute of Geography, SB RAS and the Institute of Geography and Geoecology,Academy of Sciences of Mongolia.