Abstract: The surface runoff of sites is a complex process affected by multiple variables.Factors such as rainfall, vertical design for shallow ground and pavement types are the main factors affecting the surface runoff.The site design elements will affect the above factors directly or indirectly in the process of site design,and it will optimize the surface runoff.Mainly discussing the saturation-excess runoff of site, the theoretical calculation on the conditions of saturation-excess runoff,storage spaces and the transport conditions were conducted,and the quantitative analysis on runoff combing with same cases was carried out, which could provide a quantitative analysis idea for the optimization of water factors in habitat site construction.