Focusing on the Sino-European cities, this project aims to provide tools and case studies for optimizing multimodal traffic management, improving urban mobility, reducing traffic emissions, and finding new solutions towards greener mobility practices, climate-neutral and smart cities. Based on big data, smart traffic management technologies, and integrated interdisciplinary methods, this project will build an Integrated Urban System (IUS) and key performance indicators (KPIs) for each city. With evolving urban planning, energy consumption, transport supply and demand, and group behaviours, the system will improve our understanding of interactions among urban multimodal mobility, traffic emissions, air quality and climate change, and quantify these interactions for the Sino-European cities. The results will allow to quantify the leverage effects observed, and to highlight issues of environmental justice. The system will build multi-scenario simulations, and propose multi-mode transport schemes suitable for sustainable development, simultaneously optimizing mobility, and reducing emissions and health and climate risks by introducing these KPIs. Through collaborative analyses and cross simulations, a multi-mode transport scheme suitable for the sustainable development of Sino-European cities is further proposed. The results will establish a model for building smart cities, promoting Sino-European exchanges and cooperation, and jointly exploring climate neutrality pathways under future urbanization processes.