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Abstract: Shenzhen is one of the special economic zones in China. It has been growing rapidly from rural land to an industrial city since the mid-1980s. With the process of urbanization, flooding has become a threat to the security of the city area. In this study, Buji River basin in Shenzhen Region was selected to investigate the effect of urbanization on surface runoff and peak discharge. Land use data were obtained from LANDSAT images in 1980, 1988, 1994, and 2000, and surface runoff in the same period was simulated by SCS model. Results showed that urbanization played an important factor intensifying the flood process. Increase of urbanized land and decrease of farmland might be the main reasons for increasing runoff. At 10%, 50% and 90% rainfall probability (the rainfall probability of 10% means 10-year return period of moist year, 2-year return period of normal year and 10-year return period of dry year), the increase of runoff coefficient was 12.6%, 20.7% and 33.5% respectively under relatively dry soil moisture condition, however, and the value was 2.5%, 4.3% and 6.9% respectively under relatively wet soil moisture condition. Urbanization led to obvious increase in the maximum flood discharge and decrease in runoff confluence time. At 1%, 2% and 5% rainfall probability, the increase of the maximum flood discharge was 20.2%, 23.0% and 28.9% respectively, under relatively dry soil moisture condition. The corresponding value was 1.3%, 1.6% and 2.6% respectively under relatively wet soil moisture condition. Due to urbanization in the past 20 years, runoff coefficient increased 13.4% and the maximum flood discharge increased 12.9% on average. [Copyright &y& Elsevier]