Suzhou is one of the major cities in Yangtze River Delta, China. In recent years, severe urbanization has led to serious human-land conflicts between economic development and ecological environment and arable land occupation in Suzhou. Based on GIS and RS technology, this research investigates the composition and changes of the land structure of the LULC in Suzhou at the spatial and temporal scales between 1991 and 2021, and NDTI water quality measures are used to keep track of the turbidity of the water in Taihu Lake and the watersheds surrounding. The results show that the expansion of urban area in the LULC of Suzhou has been mainly at the expense of the reduction of agricultural land, while the urbanization process has slowed down and the ecological environment has been restored to some extent in the last decade due to the government's attention. This study analyzes the changes in LULC in Suzhou over a long-time span and provides decision support for the government's future rational use of land resources and urban planning and management, as well as solutions for maintaining sustainable urban development and ecological balance.