Facing challenges in urban low-altitude traffic regulation such as decentralized operators, disordered flight activities, and frequent airspace conflicts, this study designs and implements a low-altitude intelligent traffic management system (LITMS) for urban environments. The system adopts a “user side + management side” dual-end collaborative architecture: The user side enables whole-process electronic management including aircraft/operator registration and flight plan submission through a one-stop service portal; the management side builds a city-level digital twin platform based on multisource heterogeneous data (including unmanned aircraft dynamic data, three-dimensional [3D] real-scene models, laser point clouds, and meteorological information) to achieve large-scale flight dynamic monitoring and alert warnings. In practical deployment in Chengdu, the system successfully completed real-time monitoring of over 2 million unmanned aircraft flights in 2024, verifying its reliability and practicality in complex urban environments. The research results provide an effective technical solution and implementation example for urban low-altitude intelligent traffic management, which is of great significance for promoting the standardized development of urban air traffic.