Oases are important habitats for human survival and development in northwest arid China; however, they are fragile. To realize ecological construction and sustainable development in northwest China, an analysis of the economic and ecological benefits of the oasis system with a focus on sustainability and land use optimization of oasis agro-economic systems are needed. This paper selects Fukang City as a study area. It is located on the northern slope of Mt Tianshan, Xinjiang Uygur Autonomous Region. The authors discuss the ecological and economic benefits of the oasis system, annual variation and establish an optimized allocation scheme of oasis land use structure in Fukang City based on emergy analysis and linear programming modeling. From 1996 to 2006 the oasis system was in a weak sustainable development state. Ecological and economic benefits analysis of the oasis system based on emergy analysis shows that the development of an oasis system in Fukang City is restricted by land, climate and water resources, being a typical example of the high-input and low-output type. The comparative advantage analysis of oasis cropping based on economics and ecological economics shows that the farming structure will vary across different goals. If the maximum ecological efficiency is pursued, farming structure is determined by emergy density; and if the maximum ecological and economic benefits with limited water resources are pursued, farming structure is determined by the emergy value per unit area of irrigation.