The rainstorm weather seriously affects the operation of urban traffic, and the surface gathered water and its obstruction to vision lead to a decrease of road capacity. Based on the weather data and coil detector data in Shenzhen, this study compared the urban traffic flow characteristics under rainstorm, light rain, moderate rain and normal weather conditions, and their flow-density relationships were analyzed based on the Green-shields model. Moreover, the road capacity reduction coefficients for urban arterial and sub arterial roads were quantitative calculated respectively. The results can provide theoretical support for the emergency management of urban traffic operation under rainstorm weather
