Abstract: In this paper, the Decision Tree method was used to classification of salt affected soil in Weigan-kuqa river delta oasis with the integration of high spatial resolution ALOS image and the ancillary data such as geologic maps, soil maps, groundwater table and quality data, based on their characteristic.The amount, spatial distribution, extent and center of salt affected soils in the study area was indicated, and the causal analysis of the salinization was discussed. The result showed that the total accuracy of Decision Tree classification is 91.3569%, testifying it is a very useful method for monitoring soil salinization in the arid area. The salt affected soils are mostly distributed the lower reaches of Weigan river and Kuqa river d, the north of the Tarim river and the southeast, south, east and southeast of the Weigan-Kuqa river oasis. The proportion of the salt affected soils in the study area is very high, among them Kuqa County is severely salinized, Shaya County is moderately salinized, Xinhe County is slightely salinized. The salinization in the study area was mainly due to the drought climatic conditions, rich salt origins, enclosed basin, fragile water cycle system and unreasonable human activities.