The key to effectively control salinization is to deeply understand the spatial-temporal distribution of water and salt at the regional scale after large-scale water-saving and salt control in arid oasis. Yanqi Basin in northwest Xinjiang of China was selected as the research area. LandSat remote sensing and field sampling water and salt data were used to analyze the water and salt migration and accumulation process after large-scale water-saving under changing environment. A total of five indicators, including surface salinity, soil salinity, groundwater salinity, surface irrigation, and groundwater depth were selected in 2000, 2005, 2015 and 2020. The weights of each indicator factor were determined by extension analytic hierarchy process. With the help of ENVI and ArcGIS software, spatial distribution raster maps of each indicator factor were obtained, and each raster map was standardized, the space was nested and superimposed according to the weight of each index factor, so as to get the spatial-temporal distribution of water and salt in the regional scale. The results showed that the salinization in the study area experienced three stages: expansion in 2000—2005, shrinkage in 2005—2015 and stabilization in 2015—2020. The areas with serious salinization were mainly along Bostan Lake, especially Bohu County in the west and Heshuo County in the north of Bostan Lake. Overall, the area of mild saline land was the largest, accounting for 6.17%~11.39%, followed by moderate saline land, accounting for 3.08%~10.65%, the area of heavy saline land was the smallest, accounting for 0.56%~1.10% during 2000—2020; the weight of each factor affecting the spatial-temporal differentiation process of water and salt on a regional scale was ranked as follows: groundwater depth (0.325), groundwater salinity (0.282), soil salinity (0.198), surface salinity (0.184), and surface irrigation (0.031). Groundwater depth and groundwater salinity were the main driving factors affecting the spatial-temporal differentiation of water and salt at regional scales. From the interpreted salinization development trend, the salinization in the study area was alleviated and tended to be stable. 