There are many ways to assess the impact of protected area (PA) in the conservation of the natural environ-ment. Some of them are based on information about the flora and fauna, soils, water bodies, climatic processes and phe-nomena; others – on landscape, spatial, ecosystem data. The generalization of the existing approaches into a single scheme for assessing the environmental significance of protected areas is considered as an urgent task, both from a theoretical and practical point of view. The proposed methodology is based on a set of typical open data sources, including both research by inside and outside scientific teams, and stock, statistical information published by government authorities. It allows to apply the methodolody to any protected area with an average and high degree of knowledge’s state. The im-portance of each protected area is proposed to be considered at least at 3 levels: regional, national and global. The pro-posed methodology includes the identification of the value of protected areas in terms of conservation of biota, abiotic components, natural complexes, maintaining ecological balance. In the second part of the article, the approach is applied on the example of the «Visherskiy State Nature Reserve». At the regional level, the «Visherskiy State Nature Reserve» is the most valuable protected area in the Perm region. For example, more than 30% of all species of fungi, vascular plants, fish and more than 50-60% of lichens, bryophytes and mammals found in the Kama region, live in the «Visherskiy» State Nature Reserve. In Russia and Europe, the role of Visherskiy Reserve can be characterized as significant, and in certain parameters (for example, as a site for the conservation of the largest group of Thymallus thymallus), as crucial. At the world level, the «Visherskiy State Nature Reserve» is distinguished by the preservation of the natural environment of the Urals montane tundra and taiga of the Global200 ecoregion, the southern part of a large intact forest landscape and the presence of three globally rare species (Hucho taimen, Emberiza rustica, Rangifer tarandus). There are few promising directions for the development of the methodology: improvement of approaches to the assessment of natural complexes in climate formation, the identification of valuable hydrological (surface and underground) objects. It is also interesting to carry out assessments of other reserves, national parks, and other large protected areas, which will make it possible to compare them in detail with each other. Inflow by some new information (the distribution of rare ecosystems, numerical data on the intensity of material circulation, some poorly studied groups of biota) in the future will provide an opportunity for a more complete assessment of the conservation significance of the «Visherskiy» State Nature Reserve.