In response to issues such as ambiguous drainage paths, unclear system division of responsibilities, and low implementation efficiency in urban road drainage systems when handling rainfall in China, the operational mechanisms of the urban road drainage system, as well as the discharge pathways of runoff, were thoroughly analyzed. The capacity thresholds for Beijing’s urban road drainage system to manage rainfall in terms of preventing wet shoes , preventing waterlogging , and preventing flooding , are established. In conjunction with the monitoring and early warning systems, as well as emergency rescue measures, construction guidelines for enhancing the system’s out-of-control prevention capacity are proposed. Improvement strategies for urban road drainage systems are proposed from three perspectives: top-level planning and design of the system, enhancement of comprehensive drainage capacity, and construction of emergency management.