Abstract: Based on discussion about the definitions, concepts and classifications of oases from the references, in this paper, it is considered that an oasis is a synthetical geographical landscape area of artificial biological community relying upon the artificially water supply in an aird, sem-i arid, or arid-cold area based on human's certain purposes. This definition includes 4 intensions (concepts) ： (1) An oasis is a synthetical name of the artificial biological community area in an arid, sem-i arid or arid-cold area, which includes the residents, farmlands, forest belts, orchards, vegetable gardens, gardens, artificial grasslands, parks, lawns, livestock, poultry, buildings, etc. ; (2) Oases are the artificial outcomes inlaid in the arid peculiar vegetation areas of deserts, grasslands, lowhumid meadows, shrubberies, desert valley forsts, etc. ; (3) Oases are the synthetical geographic areas or systems including artificial community, natural landscape and cultural landscape; (4) Oases are not naturally formed but are constructed on the bases of human's ability (including science, technology and culture) and natural conditions. It is also considered that the oasis classification should accurately reflect the local natural and economic features. The type and scale of oases are mainly controlled by 6 factors, i. e. the local climate, vegetation, topography, economic property, water resources, and soil conditions. Oases should be delimited in the areas where the aridity (Kc ＝0.06Σt/r) should be higher than 1.5 (when Kc ＝1.5～3.99, the areas belong to sem-i arid ones; when Kc ≥4.00, the areas belong to arid ones; when the accumulated temperature of ≥10℃ varies in a range of 200～1600℃, the areas belong to arid-cold ones).

Key words: Oasis, definition, classification system