The main oasis agricultural area in the Northwest of China and Central Asia locates at the central of Eurasia with the biggest area and the richest type in the world. The oasis agricultural classification is one of the element tasks in oasis research. In the previous studies, the main methods for classification of oasis agriculture were based on either a single indicator or combination indicators. With these methods some valuable results have been found, which have revealed a lot of rules and deserved being followed well by successors. However, these methods couldn't cover the entire research field so as to restrict the development of the research field. Therefore an innovation of classification index system is needed. Based on proposed tree classification system for oasis agriculture according to biological and agro-ecology principles, this paper divided the oasis agricultural area in Northwest of China and Central Asia into 5 levels regarding water as the main factor. The first level of the index system is defined according to the condition of water-heat match, in one type water and heat resource meet in the same period and in the other type water and heat resource appears in different time. The second level of the index system is based on the main source of moisture, which includes two types also, one type is precipitation brought by west wind circulation and the other by pacific monsoon. The third class of parameter group is river types for irrigation, which is divided into two types; one is river from mountain-oasis-desert system and the other is coming from the outside. The fourth class of parameter group is the soil type formed by different irrigation river types, including alluvial soil caused by the sediment of Ground River and the other produced by the irrigation with underground runoff, wells and springs. The fifth class of parameter group is geographic location, the corresponding climate and so on. The classification provides fundamental theory basis for deeper understanding of ecological environment and agriculture production in different oasis agricultural areas. Classification indicator system was drawn as a tree classification map by Edraw max software. The classification distribution results were showed by ArcGIS 9.3. From analysis we can get that the oasis agriculture with type of water and heat in West north of China has better resource of light, heat and water coupling effect than the oasis agriculture with Central Asia.