The shuttle unmanned ground vehicle (UGV) is an important element in the future intelligent transportation system (ITS), which will be widely used for public transportation in various scenarios. It has been widely accepted that the shuttle UGV will significantly improve the transportation efficiency and intelligent level of ITS in the near future. This paper presents an overall architecture and system of shuttle UGV for the future ITS. The hardware architecture includes sensor, actuator and computing platform, and is built on an X-by-wire chassis. The software architecture includes environment perception, decision making and dynamics control. Reliable and accurate autonomous driving algorithms are applied to the software system, which enable the shuttle UGV to drive intelligently and perform task stably. In addition, to address the large-scale deployment of shuttle UGVs in the future, this paper also introduces the concept of cloud brain system and discusses the application and prospect of the cloud brain system in ITS. The cloud brain system can store, monitor and mine the big data generated by the shuttle UGVs, which will further improve the operational safety and overall performance of the shuttle UGV group. An open road test in an ITS test zone is conducted to validate the performance of the proposed overall architecture and system for the shuttle UGV.