Urban agglomeration is an important spatial carrier of regional economic development. It is of great significance to explore the landscape expansion and change of urban agglomeration on the Northern Slope of Tianshan Mountains for the regional economic development, urban planning and ecological security of border urban agglomeration. By using GIS, Fragstats, Dyna-CLUE and other software platforms, and based on the spatial resolution data of 30 m land use in 1990, 2000, 2005, 2010 and 2015, the landscape expansion index (LEI), expansion intensity index (UEⅡ), center of gravity transfer, multi-scenario simulation and other methods were used to analyze the landscape expansion pattern and evolution law of the urban agglomeration on the Northern Slope of Tianshan Mountains. The main results showed that: (1) from the perspective of the landscape index, the urban landscape fragmentation and the spatial heterogeneity increased and complicated of patch shape during the past 25 years in the urban agglomeration on the Northern Slope of Tianshan Mountains. (2) From the perspective of expansion mode, the urban expansion mode was mainly outlying type, followed by edge-expansion type during 1990-2015 in urban agglomeration on the Northern Slope of Tianshan Mountains. The proportion of expansion mode was different in different periods. (3) From the perspective of expansion trajectory, the center of urban expansion in urban agglomeration generally moved from the west side of Urumqi, the center of urban agglomeration, to the east. (4) From the multi-scenario simulation, Dyna-Clue model can better reflect the characteristics of urban expansion and land use change of urban agglomeration in different scenarios. The multi-scenario simulation showed that the expansion mode of urban agglomeration would be mainly outlying type and edge-expansion type in 2025. The research results can provide reference for the future development and layout planning of urban agglomeration on the Northern Slope of Tianshan Mountains, and provide decision-making basis for the management and regulation of territorial space and the layout optimization of ecological environment.