Abstract: Taking Suzhou City, a typical city characterized by plain river network area in the lower reaches of the Yangtze River Delta, as an example. Based on the remote sensing images of the 1970s, the 1990s and the 2010s and the river system data of the 1960s, the1980s and the 2010s, streams structure parameters were adopted to analyze the disturbance of different urban expansion modes on different levels of rivers. Meanwhile, the evolvement relationship between spatial expansion of the city and river system structure was revealed. Research shows that: (1) Urban sprawl has the characteristics of stage and trend, and is affected and restricted by natural environment and social economy; (2) The transformation and evolution of river system shows regional differences under different stages of urbanization. River density, water surface ratio and other streams structure parameters have changed greatly in raptly urbanized area in recent years; followed by areas urbanized in the 1980s; while old town in highly urbanized stage had the smallest change and increased slightly. In the 1960s-2010s, the change range of river network density in above three districts was -21.06%, -16.23% and 1.88%, respectively. (3) The development of the river structure is significantly affected by urbanization process. The structure of the river network in the natural state is relatively stable, and after entering the urbanization stage, the stability of river structure is reduced. This study can provide reference and theoretical support for river system protection, urban planning and flood prevention and mitigation in urbanized areas.