Evaluating the available amount of rainwater resources is a crucial part of utilizing rainwater resources in solving the water problems in the process of urbanization.In order to support the utilization of rainwater resources in the Guanlan River basin in Shenzhen,we calculated the amount,the theoretical potential and the practical potential of rainwater resources in different typical years based on the daily rainfall data of Shenzhen from 1984 to 2018 by using a calculation method based on classifying the types of underlying surface.Results demonstrate that the Guanlan River basin has a large potential in the utilization of rainwater resources,with the theoretical potential in normal flow year reaching 374 million m³ and the practical potential at a 70% control rate of total annual runoff amounting to 242 million m³.Under equivalent rainfall conditions,the underlying surface and the urban construction conditions both exert remarkable influence on the available rainwater resources.Expanding underlying surface area such as landscaping area and water area and raising the control rate of total annual runoff are conducive to improving the practical potential of available rainwater resources.