Abstract: By taking the objective ecological system as the subject and applying the ecological fundamentals and meth-ods, the eco-regionalization is to reveal the similar and the diversfied laws of eco-environment, and to divide thedfferent regional units based on a full consideration of human activities. Its purposes are to provide the scientificbasis for the rational distribution of the industrial structure in the different regions, the social and economic de-velopment, the evaluation on the eco-environment and its synthetical improvement, and to provide the importanttheoretical bases for rationally exploiting and utilizing the regional resources, protecting the biodiversification, and controlling natural disasters, thus to serve the social and economic sustainable development. Hierarchicaltheory is a fundamental principle for ecosystem classification. Ecoregions are large ecosystems of regional extentthat contain a number of smaller ecosystems. Besides the identities of natural ecosystems, human factor must al-so be considered, as it is one of the primary driving forces for most of natural ecosystems changed.
As a most important strategic developmental region in China in the 21 st, the economic development ofWestern China is nearly related to the whole national economy. However, when we take full advantage of itsnatural resources and develop its economy, in the meanwhile, we must also pay great attention to protect its eco-logical environment and guarantee the social economy reach to sustainable development. Ecological regionaliza-tion and ecological mapping of Western China can provide the framework for making policies of environmentalmanagement and sustainable development in this region. In this paper, climate (temperature, precipitation andevaporation), landforms, vegetation types, soil types, human factors and so on are selected as quantitative andqualitative indices to classify different ecoregion by using ecological principles and methods. As a result, WesternChina is divided into 7 ecoregions: (1) ecoregion of rain forest in tropic northern edges, (2) ecoregion of sub-tropical humid and sub-humid evergreen broad-leaf forest in Yunnan-Guizhou plateau, (3) ecoregion of subtropi-cal evergreen broad-leaf forest in Sichuan basin, (4) ecoregion of northern subtropical evergreen-deciduous broad-leaf forest, (5) ecoregion of warm temperate forest-grassland in Loess plateau, (6) ecoregion of arid and sub-ariddesert in Northwestern China and (7) ecoregion of alpine meadow and steppe in Tibetan plateau. Moreover, 22 sub-ecoregions are also classified under the ecoregions. Finally, the characteristics and stratagems of economicdevelopment and environmental conservation in each sub-ecoregion are discussed.

Key words: eco-regionalization, development, countermeasure, Western China