In view of change of entropy in ecosystem, this paper focuses on elaborating the method of comprehensive evaluation and rational regulation to eco-environment of oasis, which meet the demands of factorial quantification and suit the integrated evaluation of natural-economic-social attribute, soas to lay the foundation of restoration and rehabilitation of eec-environment of oasis. According to dissipative structure theory advanced by Prof. Prigogine, entropy and change of entropy in ecosystem can be defined as S=Q/P, and △S=S₂-S₁-S₁₂, where S stands for entropy of ecosystem, Q stands for energy output (or input), P stands for economic income (or expenses), S₁ stands for primary entropy of ecosystem, S₂ stands for final entropy of ecosystem, S₁₂ stands for intermediate entropy of ecosystem, that is, it is also negative entropy flow which ecosystem in a motion state get from external environment, and △S stands for change of entropy in ecosystem in a motion state. Supposition the total of change of entropy in ecosystem △S= 0, and Y=S₁₂, namely Y= S₂-S₁, where Y is entropy production of inside of ecosystem or stability of ecosystem, which can be used to describe good or bad about structure and function of ecosystem. With case of Wuwei City, Gansu Province, based on the principle of stability, simple, integrity and territory, percentage of forest coverage (x₁), the proportion of cultivate grass area in cultivated area (x₂), desertified land area (x₃), soil erosion area (x₄), the proportion of ensured irrigated area in cultivated area (x₅) and depression depth of ground water table (x6) can be chosen as independent variable, and stability index of ecosystem (y) as dependent variable, a multivariate nonlinear regression equation is given by the applied of stepwise regression analysis. Thus, the evaluation for ecosystem of oasis should focused on the change of entropy in ecosystem △S and stability of ecosystem Y, and the regulation for one could obtained from the solution of ∂_y/∂_x1 =0. The results of comprehensive evaluation for ecological environment of oasis are given as follows: 18 village (town) are classified Ⅱ, 15 village (town) Ⅲ and 5 village (town) Ⅳ, and entropy values of stability of ecosystem are 26.14-29.06×10⁶, 29.43-34. 92×10⁶ and 37. 32-47. 13×10⁶ calorie/yuan (RMB) respectively. On the basis of the contribution or weight of each evaluating factor to stability of ecosystem of oasis, some managagerial strategy for ecological environment of oasis such as reverse of desertified land, strengthening conservation of water and soil, rehabilitation of shelter forest system, increasing cultivate grass area, control depression range of ground water table and stabilization ensured irrigated area are put forward.